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Flashcards in Final Exam Deck (144):
1

All COPII vesicles interact with ____

Sec24

2

some intergral ER membrane proteins are targeted to _____ vesicles for transport to ____

COPII, Golgi

3

certain intergral ER membrane proteins also bind ___ proteins in the ____

cargo proteins, lumen

4

Microtubules act as "____ ____" for large aggregates of transport vesicles

railroad tracks

5

COPI vesicles have ___grade trasnport and transport from ___-____ to ______

retrograde transport; from cis-Golgi to rough ER

6

ER-resident proteins may assist in what?

folding and modification on newly synthesized secretory proteins

7

most ER-resident proteins contain ____ sorting sequene

KDEL

8

KDEL sorting sequence is located at the _-terminus

C-terminus

9

where do ER-resident proteins bind

to complex of COPI vesicles

10

The Di arganine sequence can also target what?

certain proteins to COPI vesicles

11

what is cisternal maturation

like an assembly line, proteins move in sequence through the compartments which each house different enzymes

12

cisternal maturation is responsible for ____grade transport

anterograde

13

anterograde trainsport is from __ - ___ golgi

cis tor trans Golgi

14

cis-Golgi protein ____ is fused to ___

Crg4, GFP

15

trans-Golgi protein ___ is fused to ___

Sec7, DsRed

16

Resting membrane potential depends largely on flow of what

K+ ions

17

What is the usual resting membrane potential

60-70 mV

18

simple diffusion rate is proportional to what

concentration gradient, hydrophobicity and size

19

post translational translocation ATP hydrolysis is required by what

BiP

20

Hsp70 has a similar function to what

BiP

21

Wht are adaptor protein complexes

determines which cargo proteins are in a vescile by binding cytosolic domains of membrane proteins

22

what are the cytoplasmic sorting signals in COPI vesicles

KKXX and di-arganine

23

what is the protein that assebles and disassembles COPI coat

ARF

24

What is the AP3 complex

vesicles that bud from trans-Golgi en route directly to the lysosome

25

T or F:the AP3 complex uses the ARF protein

T

26

What do clathrin coated vesicles do

AP1-vesicles that bud from trans-Glgi en route to late endosome

27

What does GGA do

buds from trans-golgi network to late endosome

28

What does AP2 do

buds from plasma membrane during endocytosis

29

What is the Sorting signal in clathrin coated vesicles

YXXo

30

What are the five destinations of Adaptor protein complexes

COPI vesicles, AP3 complex vesicles, Clathrin coated vesicles, constitutive secretory vesicles and regulated secretory vesicles

31

___ pinches off clathrin coated vesicles

dynamin

32

what do constitutive secretory vesicles do

transport secreted protein and plasma membrane proteins to plasma membrane

33

what do regulated secretory vesicles do

store and process secreted protein until signaled to fuse with the plasma membrane to secrete proteins

34

What are the two domains of polarized epithelial cells

Apical and basolateral

35

What is between apuical and basolateral membranes to prevent povement

tight junctions

36

how are apical and basolatreal bound membrane proteins sorted

initally transported together in trans-golgi network by COPII and cisternal maturation, sorted into transport vesicles with v-SNAREs and Rab proteins

37

Influenza glycoprotein only found on ___ membrane

apical

38

VSV G protein only found on ____ membrane

basolateral

39

what helps membrane proteins associate with clatharin adapter proteins

Tyrosine and di-leucin based motifs

40

proteins targeted to apical membrane often have ___ membrane anchor

GPI

41

what is transcytosis

apical proteins move in vesicles across the cell and fuse to apical membrane

42

what visualizes protein size and abundacne

SDS-PAGE

43

what is the ionic detergent in SDS PAGE

SDS

44

what is receptor mediated endocytosis

small vesicles invaginate from plasma membrane

45

what are the four types of lipoporteins

chylomicrons, VLDL, LDL and HDL

46

What do chylomicrons do

transport triglycerides from the diet

47

What do VLDLs do

transport triglycerides made by liver, cells remove triglycerides becoming LDL

48

What do LDLs do

less healthy, deliver cholesterol to tissues

49

what do HDLs do

return excess cholesterol from tissues back to liver

50

Receptors contain ______ taht target them for endocytosis

sorting signals

51

LDL receptors release ___ at low pH

apoB-100

52

HIgh plasma LDL leads to ___

disease

53

What is the transferrin receptor complex

functions to deliver iron to cells

54

waht is apotransferrin

no iron bound

55

what is ferotransferrin

full transferrin, two Fe3+ bound

56

waht is the transferrin receptor

binds ferrotransferrin and initiates endocytosis

57

what do lysosomes do

degrade extracellular materials taken up by the cell

58

Where do normal transport vesicles bud

outward from organelle membrane to the cytosol

59

where do internal vesicles bud

inward from endosomal membrane to the lumen

60

most cargo protein destined to enter a multi vesicular endosome are tagged with what?

a single ubiquitin molecule

61

Retroviruses required ______ complexes to bud from plasma membrane

ESCRT

62

What is the purpose of autophagy

serves to recycle macro molecules to serve as nutrients under stressful conditions

63

how does autophagy work

envelopes a region of cytoplasm or organelle into double membarne for delivery to lysososme

64

What is the most important key to supporting the needs of the cell

the cytoskeleton

65

What are the three components of the cytolskeleton

microfilaments, microtubules and intermediate filaments

66

how is the cytoskeleton function regulated

cells sense extracellular signals and interpret them to direct arragement of the cytoskeleton

67

What happens to the cytoskeleton in the abscence of extracellular signals

the cells do not become polarized, but the cytoskeleton stillforms

68

What is the building block of microfilaments

actin

69

T or F: microfilaments have reverible assembly

T

70

What is actin

it is an abundant intracellular protein in eukaryotic cells

71

What are the three different groups of actin

alpha beta an y actin

72

What is alpha actin

for contractile sturctures

73

waht is beta actin

cell cortex and leading edge of motile cells

74

what is y actin

is on stress fibers

75

Each actin molecule contains a ____ ion

Mg 2+

76

What are the two forms of Actin

G-actin and F-actin

77

Actin is a _____ase

ATPase

78

What is G-actin

monomer separated by 2 lobes by a deep cleft, ATPase fold is the site of ATP and Mg binding, denatures quickly. addition of cations induces filament formation

79

what is F-actin

subunits in actin fillaments arranged in helical strands wound around each other, ATP binding clefts all oriented towards - end. Each subunit contacts one above and one below

80

The + end of microfilaments is favoured for the addion of what

actin subunits

81

The - end of microfilaments is favoured for what

unit in disocciation; ATP binding cleft exposed to surrounding solution

82

Where on the microfilament does Myosin attach

to the sides of microfilaments with a slight tilt

83

T or F: actin binding proteins contribute to staiblity

T

84

T or F: G-actin can be purified at low concentration

F: high

85

what are the three steps in actin polymerization

Nucleation phase, Elongation phase and Steady State phase

86

Filaments grow __x faster at + end than - end

10x

87

When ATP-G-actin binds to the + end, what happens

ATP is hydrolyzed to ADP and Pi

88

What are the three actin binding proteins

Profilin, cofilin and Tymosin-B4

89

What des profilin do

helps nucleotide exchange so ATP actin is ready for the (+) end

90

What does cofilin do

Specifically binds ADP-F-actin, fragemnts ADP-actin filament regions, enhancing depolymerization

91

What does Thymosin-B4 do

provides a buffered reservoir of ATP-G_actin for polymerization

92

What are the two capping proteins

CapZ and Tropomodulin

93

what does CapZ do

blcoks assembly and disassebly, caps (+) end

94

Waht does Tropomodulin do

binds (-) end, inhibits assembly and disassebly

95

actin nucleating proteins are conducted by which two signal transduction pathways

Formin and Arp2/3 complex

96

how is formin regulated

RBD binds to Rho-GTP, exposing FH2 to nucleate new filament, FH1 domain recruits profilin-ATP-G-actin
in active site is where FH2 domain inhbitied

97

what is the Arp2/3 complex

seven subunites that nucleate assembly of branced actin, bust me activated by NPF

98

Filaments grow at their (+) end until what?

capped by CapZ

99

certain toxins affect actin by promoting ______ or ______ of filaments

depolymerization and polymerization

100

What is needed to form filaments into bundles or networks

actin cross-linking proteins

101

What is myosin?

actin-based motor protein

102

what do mysoins do

move along actin filaments and convert energy from ATP hydrolysis to do work

103

To or F: different myosins perform different functions

T

104

what are the three types of Myosin

Myosin II, I and V

105

what is myosin II

protein complex of six polypeptide subunits; 2 heavy chains and 2 light chains

106

what is myosin I

one single headed myosin, encoded by eight different human myosin genes

107

what is myosin V

two head domains and six light chains per neck. encoded by three different myosin genes

108

what do myosins use for coupling ATP hydrolysis

cross-bridge cycle

109

how many profilaments in a microtubule

13

110

what is the major protein in microtubules

tubulin

111

what happens to GTP in alpha tubulin

is trapped and never hydrolyzed or released, exposed at - end

112

what happens to GTP in beta tubulin

can be hydrolyzed to GDP and exchanged for free GTP, exposed at + end

113

alpha tubulin contacts with alpha tubulin of neighbouring except at the _____

seam

114

microtubules are assembled from specific sites called

mixeorubule organizing centers (MTOCs)

115

Generally, the __ end stays anchored to the TMOC while the __ end stays away from it

-, +

116

what is the main MTOC of animal cells

Centrosome

117

waht is the main MTOC for cilia and flagella

Basal body

118

what is the structure of a singlet centrosome

nine linked triplet microtubules

119

what forms the template for the (-) end

Y-tubulin ring complex

120

dyanimc instabliity depends on the presence or absence of what

GTP-B-Tubulin cap

121

disassembly pauses when?

GTP-B-Tubulin is found on the microtubule and starts assembly phase

122

what is the difference between GTP-B-tubulin cap and GDP-B-tubulin cap

GTP promotes assebly while GDP promotes disassembly

123

There is assembly to disassembly when GTP hydrolysis rate __ GTP tubulin action

>

124

There is disassembly to assembly when GTP hydrolysis rate __ GTP tubulin action

125

what may stabilize or destabilize microtubules

mirotubule-assocated proteins (MAPs)

126

Spacing reflects difference between the lenghts of the ___ and ___ projection domains

MAP and tau

127

what do (+) end-binding MAPs do

enhance plymerixation at (+) end, reduce frequency of catastrophes link microtubules to other cell structures

128

What is the Kinesin-13 family

bind and curve the + end of profimalents into GDP-B-tubulin, require ATP for hydrolysis

129

when kinesin binds to dimers, what happens?

it curves them so curvature is that of disassembly

130

T or F: organelles move along microtubules in either direction

T

131

What are the microtubule based motor proteins

Kinesin and Dynein

132

how do kinesin and dynein move along microtubules

using ATP hydrolysis

133

What is Kinesin 1

tail doamin binds to receptors on cargo, head domain binds microtubules and ATP

134

T or F: kinesin 1 always tansports vesicles from (-) end to (+) end of a microtubule

T

135

what happens in the inhibited form

had folds back and interacts with tail, inhibits ATPase activity

136

how is kinesin-1 regulated

motor binding to vesicle receptor unfolds kinesin activating ATPase actity
transports cargo toward + end

137

T or F:there is convergent evolution between mysoin and kinesin

T

138

dynein transports organellees towards the (_) end

-

139

how many AAA ATPase domains in the dynein head

six

140

what is the dynactin complex

cytpoplasmic dynein cant bind to cargo on its own, so uses dynein complex to link dynein to cargo

141

dynactin complex contain what

one actin subunit and capZ at + end

142

the direction of organelle transport is determined by the _____

motor protein

143

Retrograde transport of late endosome is by __________

cytoplasmic dynein

144

Anterograde transport of seceretory vesicle by ______

kinesin