Final Exam Flashcards
1
Q
All COPII vesicles interact with ____
A
Sec24
2
Q
some intergral ER membrane proteins are targeted to _____ vesicles for transport to ____
A
COPII, Golgi
3
Q
certain intergral ER membrane proteins also bind ___ proteins in the ____
A
cargo proteins, lumen
4
Q
Microtubules act as “____ ____” for large aggregates of transport vesicles
A
railroad tracks
5
Q
COPI vesicles have ___grade trasnport and transport from ___-____ to ______
A
retrograde transport; from cis-Golgi to rough ER
6
Q
ER-resident proteins may assist in what?
A
folding and modification on newly synthesized secretory proteins
7
Q
most ER-resident proteins contain ____ sorting sequene
A
KDEL
8
Q
KDEL sorting sequence is located at the _-terminus
A
C-terminus
9
Q
where do ER-resident proteins bind
A
to complex of COPI vesicles
10
Q
The Di arganine sequence can also target what?
A
certain proteins to COPI vesicles
11
Q
what is cisternal maturation
A
like an assembly line, proteins move in sequence through the compartments which each house different enzymes
12
Q
cisternal maturation is responsible for ____grade transport
A
anterograde
13
Q
anterograde trainsport is from __ - ___ golgi
A
cis tor trans Golgi
14
Q
cis-Golgi protein ____ is fused to ___
A
Crg4, GFP
15
Q
trans-Golgi protein ___ is fused to ___
A
Sec7, DsRed
16
Q
Resting membrane potential depends largely on flow of what
A
K+ ions
17
Q
What is the usual resting membrane potential
A
60-70 mV
18
Q
simple diffusion rate is proportional to what
A
concentration gradient, hydrophobicity and size
19
Q
post translational translocation ATP hydrolysis is required by what
A
BiP
20
Q
Hsp70 has a similar function to what
A
BiP
21
Q
Wht are adaptor protein complexes
A
determines which cargo proteins are in a vescile by binding cytosolic domains of membrane proteins
22
Q
what are the cytoplasmic sorting signals in COPI vesicles
A
KKXX and di-arganine
23
Q
what is the protein that assebles and disassembles COPI coat
A
ARF
24
Q
What is the AP3 complex
A
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
