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Cell Bio (BIOL 4004) > Exam 2 > Flashcards

Exam 2 Flashcards

1
Q

ATPase which provides energy for the retrotranslocation of misfolded proteins from the ER to the cytosol.

A

AAA-ATPase

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2
Q

Enzyme which ‘activates’ fatty acids by the addition of CoA.

A

Acetyl-CoA ligase

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3
Q

Enzyme which catalyzes the attachment of Co-A-linked fatty acids to glycerol 3-phosphate

A

Acyl transferase

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4
Q

BiP

A

Hsp70-like chaperone protein, located on the lumenal side of the ER membrane, which pulls proteins through the protein translocator via ATP-driven cycles of binding and release. This protein also functions as a chaperone protein which recognizes and binds to incorrectly folded proteins, preventing them from aggregating or leaving the ER.

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5
Q

Calnexin

A

Membrane-bound ER chaperone protein which binds to the carbohydrate domains of unfolded ER proteins, preventing the proteins from leaving the ER.

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6
Q

Calreticulin

A

Soluble ER chaperone protein which binds to the carbohydrate domains of unfolded ER proteins, preventing the proteins from leaving the ER.

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7
Q

Chaperone proteins

A

proteins that bind to others to regulate folding

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8
Q

co-translational translocation

A

translation and translocation of a protein into the ER happening at once

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9
Q

cytoplasm includes

A

cytosol and organelles

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10
Q

E3 ubiquitin ligase

A

Enzyme which attaches polyubiquitin tags to unfolded proteins as they exit a protein translocator and enter the cytosol
* marking the protein for destruction by proteasomes.

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11
Q

ER retention signal

A

Four amino acid sequence at the C-terminal of a protein which prevents it from being translocation from the ER to other organelles.

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12
Q

ER signal peptidase

A

Enzyme, closely associated with the ER protein translocator, which cleaves ER signal sequences from translocating proteins.

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13
Q

flippase

A

specific flipper of plasma membrane, results in asymmetric lipid bilayer

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14
Q

free ribosomes function

A

in the synthesis of cytosolic proteins

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15
Q

glucosidase cleaves

A

terminal glucose residues from N-linked oligosaccharides in the ER

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16
Q

ER enzyme which adds a glucose residue to ER proteins that are not properly folded.

A

Glucosyl transferase

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17
Q

Glycosylphosphatidyl-inositol (GPI) anchor

A

A glycolipid which can be attached to the C-terminus of a protein in the ER lumen; when transported to the plasma membrane the protein will be displayed on the cell surface.

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18
Q

Mitochondrial Hsp70 function

A

binds to imported proteins as they emerge from the TIM channel, and helps ‘pull’ the protein into the matrix space using the energy of ATP hydrolysis.

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19
Q

Mitochondrial Hsp70 is part of the

A

TIM translocator

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20
Q

N-glycanase

A

Enzyme which removes oligosaccharides chains from ER proteins that have been retrotranslocated into the cytosol.

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21
Q

N-linked oligosaccharides are _ linked to _ residues of _

A

Oligosaccharides covalently linked to asparagine residues of proteins.

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22
Q

nucleoporins are composed of and orientated

A

repetitive domains and orientated symmetrically across nuclear envelope

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23
Q

Nuclear basket

A

Network of fibrils which protrude from nuclear pore proteins into the nucleus and cytosol.

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24
Q

Nuclear export receptors (exportins)

A

Receptors which bind to nuclear export signals and NPC proteins; they function in the translocation of proteins from the nucleus to the cytosol.

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25
Q

Nuclear export signals direct

A

translocation of proteins from nucleus to cytosol

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26
Q

Nuclear import receptors (importins) bind to

A

NLS and NPC proteins

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27
Q

Nuclear import receptors (importins) function in

A

translocation of proteins from the cytosol to the nucleus

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28
Q

Nuclear localization signals (NLS) directs

A

proteins from cytosol to the nucleus

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29
Q

Nuclear pore complexes (NPCs)

A

Arrangement of protein subunits which function to regulate the gated transport of proteins between the cytosol and the nucleus.

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30
Q

Oligosaccharyl transferase

A

Enzyme that transfers a precursor oligosaccharide from membrane-bound dolichol to certain asparagine residues of proteins imported into the ER.

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31
Q

OXA complex

A

Mitochondrial inner membrane translocator which mediates the insertion of mitochondrial encoded proteins and nuclear-encoded matrix proteins into the inner membrane.

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32
Q

PERK kinase, ATF6 and IRE1 kinase

A

Three ER membrane proteins which sense, and are activated by, an accumulation of unfolded proteins

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33
Q

_ carry out the unfolded protein response

A

PERK kinase, ATF6 and IRE1 kinase

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34
Q

Phosphatidic acid

A

This phospholipid precursor is formed by the attachment of glycerol 3-phosphate to two membrane fatty acids.

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35
Q

Phospholipid exchange proteins (phospholipid transfer proteins)

A

Water soluble carrier proteins involved in the transport of lipids from the ER to mitochondria.

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36
Q

Porins

A

Beta-barrel proteins which form large pores in the outer mitochondrial membrane, making it freely permeable to inorganic ions and metabolites.

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37
Q

Proteasomes

A

Cytosolic structures where poly-ubiquitylated proteins are degraded.

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38
Q

Enzyme which catalyzes the oxidation of free sulfhydryl groups of cysteines residues to form disulfide bonds.

A

Protein disulfide isomerase (PDI)

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39
Q

GTPase (molecular switch) which functions in the regulation of nuclear import and export.

A

Ran GTPase

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40
Q

Ran GTPase-activating protein (Ran-GAP) converts

A

Ran-GTP to Ran-GDP

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41
Q

Ran Guanine Exchange Factor (Ran-GEF)

A

Nuclear protein which catalyzes the exchange of GCD for GTP, converting Ran-GDP to Ran-GTP.

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42
Q

Proteins which catalyze the conversion of Ran-GTPase between two states (bound GTP or bound GDP), e.g. Ran-GAP and Ran-GEF.

A

Ran-specific regulatory proteins

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43
Q

Retrotranslocation (dislocation)

A

Translocation of misfolded ER proteins back to the cytosol for degradation.

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44
Q

SAM complex

A

Mitochondrial outer membrane complex which helps outer membrane β-barrel proteins fold correctly.

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45
Q

Sec61 complex

A

Protein complex which forms the aqueous core of ER protein translocators.

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46
Q

Signal-recognition particle (SRP)

A

Ribonucleoprotein complex which binds to an ER signal sequence as it emerges from the ribosome, halts further translation, and guides the ribosome to receptors on the ER membrane.

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47
Q

TIM22 complex

A

Mitochondrial inner membrane protein translocator which mediates the insertion of some proteins into the inner membrane.

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48
Q

TIM23 complex

A

Mitochondrial inner membrane protein translocator, associated with mitochondrial HSP70, which transports some soluble proteins into the matrix space, and helps insert transmembrane proteins into the inner membrane.

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49
Q

Zellweger syndrome is caused by

A

defects in the import of proteins to peroxisomes.

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50
Q

The ER, golgi, endosomes and lysosomes have lumens equivalent to

A

the exterior of the cell

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51
Q

nucleus and cytosol communicate via

A

nuclear pore complexes

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52
Q

3 families of intracellular compartments

A
  1. nucleus and cytosol
  2. ER, golgi, vesicles, endo&lysosomes
  3. mitochondria and chloroplasts
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53
Q

if there is a protein with no signal sequence

A

it will remain in the cytosol after it is made

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54
Q

3 mechanisms of movements between cellular compartments

A
  • Gated transport
  • protein translocation
  • vesicular transport
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55
Q

gated transport is for movement between

A

cytosol and nucleus

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56
Q

protein translocation is for movement between

A

cytosol and mitochondria/chloroplasts, perixomes and ER

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57
Q

vesicular transport is for movement b/w

A

secretory and endocytic compartments

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58
Q

in vesicular transport, membrane…

A

orientation is preserved

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59
Q

in vesicular transport, _ components are transferred by

A

soluble components within the lumen of the vesicles

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60
Q

the _ is continuous with the lumen of the ER

A

perinuclear space

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61
Q

the inner membrane of the nucleus is for

A

anchoring sites for chromatin and nuclear lamina

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62
Q

outer membrane of the nuclear envelope is continuous with

A

with ER

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63
Q

transmembrane ring proteins

A

span the nuclear envelope and anchor NPCs to the envelop (6.1 pg 15)

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64
Q

scaffold nucleoporins

A

form layered ring structure (6.1 pg 15)

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65
Q

channel nucleoporins

A

line the central pore and regulate diffusion (6.1 pg 15)

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66
Q

how do cargo transfer by receptors

A

transport receptors binding to FG repeat on protein tangles then receptors pull cargo through NPC

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67
Q

how is cargo released in nucleus

A
  1. cargo with NLS binds to import receptors
  2. import receptors pull through cargo thru NPC
  3. binding of Ran-GTP promote cargo release from receptors
  4. Ran-GTP-import-receptor complex transported back to cytosol
  5. GAP make Ran-GTP to Ran-GDP
  6. import receptor and GDP and Ran separate
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68
Q

Import receptors: Binding of Ran-GTP…

A

promotes cargo release from import receptors

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69
Q

export receptors: binding of Ran-GTP…

A

promotes cargo binding

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70
Q

nuclear lamins is important to _ and anchored to

A

important to shape and stability of nucleus and anchored to NPCs and inner membrane proteins

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71
Q

functions of cytoskeletal folaments

A
  • provide mechanical strength
  • cell shape and polarity
  • organization
  • cellular movement
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72
Q

interactions between subunits of cytoskeletal filaments are _ so that

A

noncovalent, they are dynamic since these bonds are weaker

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73
Q

at the critical concentration…

A

rate of subunit addition = rate of subunit loss

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74
Q

in actin filaments and microtubles, subunits are added…

A

more rapidly to the plus ends than the minus ends

minus end needs more dramatic change in conformation

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74
Q

in actin filaments and microtubles, subunits are added…

A

more rapidly to the plus ends than the minus ends

minus end needs more dramatic change in conformation

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75
Q

subunits added to the polymer of actin filaments

A

ATP

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76
Q

subunits added to the polymer of tubulin

A

GTP

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77
Q

in polymer growth or shrink, nucleotide hydrolysis…

A

decreases the affinity of a subunit which means increases change of subunit disassociating from end of polymer

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78
Q

ATP/GTP cap will form if

A

the concentration of subunit higher than critical concentration

rate of subunit addition > rate of hydrolysis

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79
Q

treadmilling occurs when

A

rate subunit addition = rate of loss

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80
Q

when treadmilling,

A

polymer will move towards plus end slowly

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81
Q

protofilaments are _ and _

A

unstable and easily broken

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82
Q

lateral bonds b/w…

A

protofilaments make is so that growth/shrink is easy but breakage is not easy

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83
Q

_ is the rate limiting step in filament formation

A

nucleation

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84
Q

steps of filament formation

A

nucleation, elongation, steady state

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85
Q

nucleation is eliminated by

A

addition of filament seeds

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86
Q

microtubules functions

A
  • provide tracks for transport
  • anchoring for organelles
  • mitotic spindle seperation
  • clia and flagella
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87
Q

microtubules are formed from

A

alpha and beta tublin dimers that line up w noncovalent bonds

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88
Q

alpha tublin end

A

minus end

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89
Q

plus end of microtubules has

A

beta tubulin

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90
Q

microtubules grow faster at

A

plus ends

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91
Q

change from growth to shrinkage

A

catastrophe

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92
Q

_ are seen near plus ends of depolymerizing microtubules

A

rings of curved oligomers

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93
Q

shrinkage to growth change

A

rescue

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94
Q

high GTP means microtubules

A

grow

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95
Q

microtubules depolymerize after losing the GTP cap and if

A

GTP is below Cc

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96
Q

_ alter microtubules stability

A

plant toxins

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97
Q

gamma tublin are involved in

A

microtubule nucleation

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98
Q

microtubules are nucleated at

A

microtubule-organizing centers (MTOCs)

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99
Q

nucleation of microtubules depends on

A

gamma tubulin ring complexes which are organized into a ring and prevent loss of subunits at minus end

100
Q

in most animal cells, MTOCs called _ are

A

centrosomes are in the nucleus

101
Q

centrosomes are composed of

A

a fibrous percentriolar matrix containing gamma TuRC and two perpendicular centrioles

102
Q

microtubles growing from gamma TuRC have the _ end near

A

the minus end near centrosomes and the TuRC

103
Q

centrioles are

A
  • composed of microtubules and accessory proteins
  • make poles of spindle apparatus
104
Q

centrioles structure

A

centriolar microtubules form nine triplets in a cartwheel shape

105
Q

cells use accessory proteins to

A
  • regulate microtubule length, stability, number and orientation
106
Q

MAPs

A

microtubule associated proteins
* bind to microtubules

107
Q

the concentration of tubulin monomers is usually

A

higher than the Cc

108
Q

stathmin…

A

decreases concentration of microtubules subunits, favor depolymerization

109
Q

katanin…

A

severs microtubules near their MTOC, leading to depolymerization
* might plan a role in mitosis

110
Q

MAP2 is in _ and has _

A

dendrites and has a long projecting domain so microtubules are farther apart

111
Q

Tau is in _ and has _

A

axons and has a short projecting domain so microtubules are closer together

112
Q

microtubule motors bind to cargo with _ and bind to microtubules with _

A

cargo with tail domain

microtubules with motor/head domain

113
Q

motor/head domains functions

A
  • determine direction of motor
  • determine binding
  • hydrolysis of ATP
114
Q

microtubule motors move by

simple

A

ATP hydrolysis

115
Q

_ are minus end moving motors

A

dyneins

116
Q

_ are plus end moving motors

A

kinesins

117
Q

kinesin dimer moving processing

A
  • rear head detaches from tublin binding site by hydrolysis of ATP on back head
  • exchange ATP in, ADP out on forward head causes neck of leading head to zipper down
  • zippering down throws rear motor domain forward to next binding site

9.3 pg 5

118
Q

each motor domain of kinesis consists of

A

catalytic core and neck linker

119
Q

cytoplasmic dynein functions

A
  • movement of organelles
  • construction of mitotic spindle
  • infraflagellar transport
120
Q

axonemal dyneins function

A

function in the beating of cilia and flagella

121
Q

cytoplasmic dyneins are composed of

A

two heavy chains and multiple intermediate and light chains

122
Q

heavy chains contain

A

domains for microtubule binding and ATP hydrolysis

123
Q

intermediate and light chains help to

A

mediate dynein function

124
Q

dynein movement steps

A
  • motor domain stalk attaches to microtubule when ATP turn to ADP
  • release of ADP results in conform change and the head of motor domain and stalk rotate relative to the tail
  • this is called a power stroke

9.3 slide 8

125
Q

Dynactin

A

Large protein complex which links cytoplasmic dynein to the membranes of organelles

126
Q

Anterograde movement

A

Kinesin-mediate movement of vesicles and organelles towards axon terminals

127
Q

Retrograde movement

A

Dynein-mediated movement of vesicles and organelles along an axon towards the nerve cell body

128
Q

Centripetal movement

A

Movement of organelles and vesicles towards the cell center

129
Q

Centrifugal movement

A

Movement of organelles and vesicles towards the cell periphery

130
Q

centripetal movement is _ and mediated by _

A

rapid and smooth and mediated by dynein

131
Q

centrifugal movement is

A

a jerky tug of war between kinesin and dynein that kinesin wins

132
Q

decreasing cAMP levels results in movement of _ to _ via _ since _ is inactivated

A

decreasing cAMP levels results in movement of granules to cell center via dynein since kinesin is inactivated

133
Q

cilia beat in a

A

whip like motion
* fast power stroke is when cilium is fully extended and sweeps forward
* slow recovery stroke cilium curl backwards

like breast stroke

134
Q

_ form the core of cilia and flagella

A

axonemes

135
Q

axoneme consist of

A

nine doublet microtubules, a central singlet microtubule pair, dynein arms, nexin links and other associated proteins

136
Q

force generated by dynein causes

A

axoneme to bend

137
Q

how do nexin link function in bending of cilia

A
  • w/o nexin, doublets would slide when dynein walk
  • nexin link convert dynein energy released from conformational change into bending motion
  • they do this with cycle of de/attach b/w motor head and doublet of axoneme
138
Q

cilia and flagella arise from

A

basal bodies

139
Q

proteins from cytosol are carried _ direction toward tip of cilia by _

A

anterograde, kinesin

140
Q

primary cilia are

A

nonmotile bc no dynein arms

141
Q

primary cillium are made at

A

centrioles

142
Q

in mitosis, primary cilia

A

use centrioles as basal bodies to nucleate

143
Q

primary cilia are used in nose

A

and ears to responsd to external enviroment

144
Q

Human diseases linked to defects in cilia

A

Ciliopathies

145
Q

_ is required for all translocation of nuclear encoded proteins

A

TOM complex

146
Q

5 mitochndrial protein translocators

A
147
Q

Active nuclear import of large molecules and protein complexes depends upon the presence of _ being recognized by _

A

nuclear localization signals (NLS) being recognized by nuclear import receptors

148
Q

TOM is on the _ membrane of the mitochondria

A

outer

149
Q

TIM complexes help with

A

insertation of proteins into inner membrane

150
Q

OXA complex helps with

A

insertation of proteins into inner membrane

151
Q

SAM complex helps with

A

folding of outer membrane beta barrel proteins

152
Q

steps for protein translocation into matrix of mitochondria

A
  1. TOM recognizes SS
  2. TOM transport across outer membrane with ATP
  3. TIM23 recognize SS
  4. TIM23 transport into matrix with electrophoresis
  5. Hsp70 helps pull protein in
153
Q

Transport through TOM complex

describe

A
  • cystolic Hsp70 deliver to TOM
  • SS recognized
  • ATP hydrolysis used to release protein from Hsp70
154
Q

transport through TIM23

described

A
  • membrane potential used to pull SS through
  • release of mitochondrial Hsp70 requires ATP hydrolysis
155
Q

insertation of porins into outer membrane

describe

A
  1. transported into Intermembrane space by TOM
  2. bind to chaperon to prevent aggregation
  3. bind to SAM to insert into outer mem and fold
156
Q

translocation of proteins to inner membrane of mitochondria

describe

A
  1. SS through TOM and TIM23
  2. stop transfer sequences prevents transolcation into matrix
  3. TOM complex pulls remaining protein into IM space
  4. protein anchored by stop transfer sequence after SS is cleaved
157
Q

transportation of multipass transmembrane proteins into inner membrane of mitochondria

A
  1. TOM translocates into IM space
  2. IM space chaperone proteins guide to TIM22
  3. TIM22 weaves protein that has alternating SS and stop transfer sequences

like sowing machine

158
Q

function of peroxisomes

A
  • oxidize
  • catalasys of H2O2
  • beta oxida
  • synthesis of plasmalogens
159
Q

plasmalogens

A

lipids abundant in myelin sheaths f axons

160
Q

translocation of proteins into peroxisomes

A
  • peroxins are membrane translocators
  • import receptor proteins bind to SS, accompany cargo, release then return to cytosol
161
Q

zellweger syndrome is caused by

A

defects in the import of proteins to peroxisomes

162
Q

2 ways perioxisomes are made

A
  • budding from ER
  • fission
163
Q

the ER is a

A

branching network of interconnected tubules and flattened sacs that extends throughout the cytosol

164
Q

SER functions

A
  • synthesis of steroid hormones,
  • the detoxification of lipid-soluble drugs
  • the storage of Ca2+.
165
Q

the ER is continuous with

A

the outer membrane of the nuclear envelope

166
Q

import of ER proteins is mostly

A

co-translational

167
Q

Water-soluble proteins destine for lumens of organelles, or secretion into extracellular space are

A

completely translocated across the ER membrane into the ER lumen

168
Q

membrane bound ribosomes function in

A

co-translational translocation into the ER

169
Q

free ribosomes function in

A

synthesis of cytosoic proteins

170
Q

singal recognition particles (SRPs) are _

A

rod like ribonucleoprotein complexes with a SS binding site

171
Q

Proteins are directed to the ER by an _ , which are bound by _ as they emerge from the ribosome exit site

A

ER signal sequence,
signal- recognition particles (SRPs)

172
Q

function of translation pause domain of the SRP

A

gives the SRP-ribosome complex time to bind to the ER membrane
* makes sure protein is not released into cytosol

173
Q

SRP-ribosome complex translocation into RER membrane

A
  1. SRP binds to a SRP receptor on ER membrane
  2. ribosome is guided to protein translocator on ER membrane
  3. SRP and SRP receptor are released
  4. translation restarts and protein crosses ER membrane via translocator

6.3 page 12

174
Q

how do proteins post translationally translocate into the ER

A
  • accessory proteins are needed
  • eukar: BiP cycles of binding and release is driven by ATP hydrolysis which pulls protein into the ER lumen
175
Q

when there are more positively charged AA right before the start transfer signal, the oreintation of the transmembrane protein is

A

c-terminus in ER lumen

176
Q

when there are less positively charged AA right before the start transfer signal, the oreintation of the transmembrane protein is

A

n-terminus in the ER lumen

177
Q

tail anchored proteins translocation into ER membrane

describe

A
  • pre targeting complex recognize c terminal
  • brings it to Get3 ATPase
  • complex interactions with Get1-Get2 receptor complex in ER membrane
  • Get3 hydrolyzes ATP
  • tail anchor is inserted in membrane

6.3 pg 21

178
Q

most proteins in ER are glycosylated by

A

the transfer of a precursor oligosaccharide from a dolichol membrane lipid

179
Q

N-linked glycosylation is catalyzed by

A

oligosaccharyl transferase

180
Q

The first sugar of _ is added in the ER, and the remaining residues are added in _

A

O-linked oligosaccharides, remaining in GOlgi

181
Q

calnexin and calreticulin function

A

binding to unfolded proteins so they cannot leave the ER

182
Q

cycle of making sure protein is properly folded

A
  • calnexin/calreticulin binds unfolded protein
  • glucosidase removes final glucose and free protein from calnexin/calreticulin
  • glucosyl transferase determine if protein folded right
  • if not, add new glucose and repeat cycle
183
Q

_ determines if protein folded right

A

glucosyl transferase

184
Q

3 sensor for misfoded poteins

A
  • IRE1
  • PERK
  • ATF6
185
Q

PERK pathway

A

PERK activates
* phosphorylates/inactivates and translation initiation factor
* increased levels of a transcription regulator for UPR response

186
Q

ATF6 pathway

A

ATF6 cytosol domain cleaves and regulates transcription of UPR genes

187
Q

IRE1 pathway

A
  • misfolded protein bind to IRE1
  • ribonuclease domain activated
  • pre-mRNA made into mRNA by take out intron
  • translation of mRNA
  • makes a transcription regulator
  • upregulation of transcription of chaperon mRNA
188
Q

how lipid bilayers are assembles in the ER

A
  1. fatty acid delivered by FA binding proteins
  2. acyl transferases at 2 FA to glycerol
  3. layer bigger
189
Q

_ cannot be removed from the membrane

in lipid bilayer formation

A

phosphatidic acid

190
Q

Why are the GPI-anchored proteins of the plasma membrane always located in the extracellular space?

A

These proteins are always located in the extracellular space because enzymes in the ER covalently attach the GPI anchors to certain proteins in the plasma membrane. The linkage of these proteins and anchors occurs in the lumen of the ER which is equivalent to the extracellular space. Therefore, they are always located in the extracellular space.

191
Q

The _ is a meshwork of interconnected intermediate filament proteins that gives shape and stability to the nuclear envelope.

A

nuclear lamina

192
Q

Directionality of transport in the _ is regulated by Ran GTPase.

A

nucleus

193
Q

Acid hydrolases

A

Type of hydrolytic enzymes found in lysosomes which require a low pH environment for activity

194
Q

Lumens of membrane-enclosed compartments involved in _ and _ pathway are topologically equivalent to the _

A

biosynthetic- secretory pathway and endocytic pathway are topologically equivalent to the cell exterior

195
Q

Proteins can travel through the spaces of the organelles in these pathways without having to cross membranes

A

biosynthetic- secretory pathway and endocytic pathway

196
Q

Biosynthetic-secretory pathway

A
  • travels outward
  • ER → Golgi → cell surface or lysosomes
197
Q

Endocytic pathway

A
  • travels inwards
  • Plasma membrane → endosome → lysosome
198
Q

Retrival pathway

A

brings proteins back to original compartment

199
Q

THe _ balances the flow of membrane b/w compartments

A

retrieval pathway

200
Q

Functions of protein coats

A
  • Inner layer of coat selects and concentrates specific membrane proteins into a membrane patch
  • Outer layer of coat molds the forming vesicle
201
Q

Clathrin-coated transports

A

from plasma membrane to endosomal and golgi compartments

202
Q

COP1 coated bud from

A

Golgi

203
Q

COP2 coated vescicles bud from

A

ER

204
Q

Subunit of clathrin

A

triskelion

205
Q

Process of clathrin coated vesicle budding

A
  1. adaptor protein binds to **cargo receptor **
  2. cargo receptor binds cargo
  3. adaptor protein binds clathrin
  4. this causes bending of membrane
  5. dynamin forms a ring around the neck of the bud
  6. fusion of membrane
  7. budding off
  8. vesicle rapidly loses protein coat bc of HSP70
206
Q

PIPs are made by

A

PIs undergo rapid cycles of phosphorylation and dephosphorylation of their inositol sugar

207
Q

what regulates the binding domains of vesicular transport

A

specific PIP binding

208
Q

The distinct _ will determine which adaptor proteins will bind, and thus which cargo will be transported

A

distribution of PIPs within a membrane

209
Q

The distinct distribution of PIPs within a membrane will determine…

A

which adaptor proteins will bind, and thus which cargo will be transported

210
Q

COP2 vesicle formation process

A
  • Sar1-GDP turns into Sar1-GTP
  • this exposes the amphiphilic helix on Sar1
  • this helix binds to ER membrane
  • membrane bound Sar1-GTP binds to Sec24 and Sec23
  • membrane starts to deform
  • Sec24 binds to cargo receptors
  • Sec13 and Sec31 form outer coat of shell
  • budding off
211
Q

outer coact of COP2 shell

A

Sec13 and Sec31

212
Q

_ direct vesicles to correct target membrane

A

Rab proteins and Rab effectors

213
Q

Largest subfamily of monomeric GTPases

A

Rab proteins and Rab effectors

214
Q

how does Rab protein create specialized membrane domains

A
  1. Rab5-GDP encounters Rab-GEF and makes Rab-GTP
  2. Rab5-GTP anchores in endosomal membrane
  3. Rab5-GTP activates PI3-kinase
  4. PI to PI3P
  5. PI3P recruits Rab effectors
215
Q

how Rab alters membrane identity

A
  1. Activation of RabA-GEF
  2. RabA recruits RabB-GEF
  3. RabB-GEF recruit RabB
  4. RabB recruit RabA-GAP
  5. RabA-GAP inactivates RabA
  6. RabB replaces by RabB
216
Q

_ mediate the fusion of the lipid bilayers

A

SNARE proteins

217
Q

When v- and t-SNAREs interact…

A

helical domains wrap around each other and form stable trans-SNARE complexes which lock the two membranes together

218
Q

what makes sure vescicle docking is highly specific

A

SNARE complexes

219
Q

how does vesicle fusion

A
  1. water is expelled as two membranes pulled together by SNARES
  2. lipids form stalk
  3. lipids make fusion
220
Q

NSF ATP hydrolysis provides the energy to…

A

separate the SNARE complex

221
Q

COPII-coated transport vesicles bud off from _ , moving membrane and cargo to the _

A

ER exit sites, to the Golgi apparatus

222
Q

selective transport from the ER: membrane proteins display _ on their _ which are recognized by _

A

selective transport from the ER: membrane proteins display exit signals on their cytosolic tails which are recognized by adaptor proteins of the inner COPII coat;

223
Q

selective transport from the ER: soluble cargo proteins display _ recognized by…

A

exit signals, non-cytosolic domains of the cargo receptors

224
Q

Non-selective transport from ER is slower or faster than selective?

A

slower

225
Q

Non-selective transport from ER

A
  • ER resident proteins (lacking exit signals) may randomly enter transport vesicles, slowly leaking out of the ER to the Golgi.
226
Q

secretory proteins will be…

A

packaged in vesicles without the help of exit signals or cargo receptors

227
Q

Vesicles leaving the ER…

A

lose their protein coats, fuse with one another (homotypic fusion) via the interaction of SNAREs, and form vesicular tubular clusters.

228
Q

COPI-coated transport vesicles immediately _ and transport _

A

begin to bud off vesicular tubular clusters and transport ‘escaped’ resident proteins and cargo receptors back to the ER.

229
Q

retrieval (retrograde) transport identifies

A

resident ER membrane and soluble proteins which display retrieval signals.

230
Q

The structural integrity of the Golgi is contingent on

A

matrix proteins called golgins

231
Q

cis face

A

vescicles arrive from ER, return to ER or go in golgi

232
Q

trans face golgi

A

vescicles leave golgi network

233
Q

cis Golgi network (CGN)

A

a collection of fused vesicular tubular clusters arriving from the ER.

234
Q

Transport through the Golgi may occur by one of two mechanisms:

A

vesicular transport model (cisternae remain static) or cisternal maturation model (cisternae move)

235
Q

golgi processing has _ and _ organization which means

A
  • spatial: each cisternae contain specific processing enzymes
  • biochemical: enzymes can only act on product of previous enzyme
236
Q

High-mannose oligosaccharides

A

Oligosaccharides displaying a variable number of terminal mannose residues, all originating from the precursor oligosaccharide added in the ER

237
Q

O-linked oligosaccharides

A

Oligosaccharides containing a variable number of sugar residues linked to serine or threonine residues in the Golgi apparatus

238
Q

mucins

A

Proteins heavily glycosylated via O-linked sugars, they bind water in the lumens of organs to produce mucus

239
Q

goblet cells

A

Cells which secrete large amounts of mucin proteins into the lumens of the GI and respiratory tracts

240
Q

Vesicular transport model

A

Model of transport through the Golgi apparatus in which vesicles transport proteins between static cisternae

241
Q

Cisternal maturation model

A

Model of transport through the Golgi apparatus in which cisternae form continuously at the cis face, then migrate through the stack as they mature

242
Q

The lumens of lysosomes are filled with

A

acidic hydrolases

243
Q

acidic hydrolases require

A

acidic enviroments

pH 4.5 to 5

244
Q

_ in the lysosomal membrane uses energy of ATP hydrolysis to _ for pH of 4.5-5

A

vacuolar H+ ATPase, pump H+ ions into the lumen

245
Q

vacuolar H+ ATPase in the lysosomal membrane uses energy of

to do what

A

ATP hydrolysis to pump H+ ions into the lumen, maintaining a lumenal of pH of 4.5-5.0 (optimal for the activity of acidic hydrolases)

246
Q

Lysosomal hydrolases and membrane proteins are synthesized in the _ , pass through the _ and are delivered to _

A

ER, Golgi apparatus, endosomes

247
Q

Late endosomes contain…

A
  • material via endocytosis
  • hydrolases from golgi

Cell Bio (BIOL 4004) (8 decks)

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