1.12: Intracellular Vesicular Transport Pt 2

Question 1

which face of the golgi is the er closer to

Answer 1

the cis face

Question 2

name the cisternae in order from cis to trans face

Answer 2

cis, medial, trans

Question 3

when cargo goes from the er to the cis golgi, the adaptor proteins of the inner copII coats binds to proteins with what feature

Answer 3

those with exit signals

Question 4

are all exit signals the same

Answer 4

no

Question 5

when cargo wants to go from er to cgn, what coat is used on the vesicles

Answer 5

copII coated

Question 6

soluble proteins are bound by ____________, transmembrane proteins are bound by __________

Answer 6

soluble proteins are bound by cargo receptors, transmembrane proteins are bound by copII coat

Question 7

when cargo has no exit signal, how do they get packaged

Answer 7

due to high concentration in the er they left through diffusion

Question 8

when do copII coated vesicles shed their coat

Answer 8

after they bud from the er exit site

Question 9

what is it called when vesicles fuse together

Answer 9

vesicular tubular clusters

Question 10

where do vesicular tubular clusters go to

Answer 10

golgi

Question 11

what molecules are needed to untangle the v and t snares

Answer 11

nsf and atp

Question 12

what type of coat does retrieval/retrograde transport involve

Answer 12

copI coated vesicles

Question 13

for retrieval/retrograde transport, what do the vesicles contain

Answer 13

escaped er resident proteins, proteins involved in vesicle budding from er

Question 14

where can retrieval/retrograde transport come from

Answer 14

vesicular tubular clusters, golgi

Question 15

er resident proteins have which signals

Answer 15

er retrieval signals

Question 16

soluble er proteins have which retrieval signal and are bound by which receptor

Answer 16

KDEL, KDEL receptor

Question 17

soluble er proteins with the KDEL retrieval signal are packaged into what type of vesicles

Answer 17

copI - coated transport vesicles

Question 18

the er retrieval signals are bound by what

Answer 18

copI coats

Question 19

what is kdel receptor binding affinity regulated by

Answer 19

pH

Question 20

at what condition is kdel receptor-kdel binding affinity high and where is it high

Answer 20

binds in acidic pH, at vesicular tubular clusters and golgi the receptors have high affinity for kdel

Question 21

at what condition is kdel receptor-kdel binding affinity low and where is it low

Answer 21

kdel is released in neutral ph, and at ER there is a low affinity for kdel

Question 22

how is pH regulated in the lumens of organelles

Answer 22

v-type ATPase, H pump

Question 23

where on the signals are the receptors

which part of the protein are the signals attached to

Answer 23

on the c terminus

Question 24

do all er and golgi resident proteins have retrieval signals

Answer 24

no

Question 25

how do proteins end up in the correct compartment if they don’t have retrieval signals (2)

Answer 25

1. different transport rates: eg some golgi enzymes cycle between the er and golgi, but transport to the er at a slower rate (tends to bind better for proteins going a certain way)
2. proteins retained in resident compartment: proteins that function in the same compartment form large complexes which prevents packaging into transport vesicles

Question 26

what proteins keep transport vesicles and golgi cisternae close

Answer 26

tethering proteins

Question 27

processing of n-linked oligosaccharides occurs where

Answer 27

golgi

Question 28

describe the vesicular transport model through the golgi cisternae

Answer 28

from cis to trans: copI coated transport vesicles with cargo move forward from one golgi cisterna to the next
retrograde transport: copI vesicles return escaped resident ER proteins and golgi enzymes

Question 29

which transport model of moving proteins through the golgi cisternae is faster

Answer 29

vesicular transport model

Question 30

describe the cisternal maturation model

Answer 30

everyone get promoted: cisternae move through the golgi apparatus, vesicular tubular clusters from the er fuse to become the cgn (cis golgi network), each cisterna becomes the next, existing trans cisterna moves to the TGN
retrograde transport by copI vesicles move golgi enzymes and er resident proteins back

Question 31

what factor is common between both methods of protein transport within the golgi

Answer 31

both have the same pathway for retrograde transport

Question 32

what is the tgn

Answer 32

trans golgi network: complex network of membranes and vesicles that is a major branch point where proteins are sorted into different vesicles

Question 33

vesicles from tgn are transported where and what is the cargo

Answer 33

transported to late endosomes (late endosomes gradually mature into lysosomes) and they carry lysosomal hydrolases

Question 34

name the purpose of lysosomal hydrolases

Answer 34

needed for lysosome function and degradation of macromolecules

Question 35

where are acid hydrolases synthesized and processed

Answer 35

synthesized in the er and processed in the golgi

Question 36

what do acid hydrolases do and list some examples

Answer 36

degrade macromolecules
examples: nucleases, proteases, glycosidases, lipases, phosphatases, sulfatases, phospholipases

Question 37

how does the cell ensure its safety from the acid hydrolases

Answer 37

• it’s only active at acidic pH
• there is a membrane around the lysosome/endosome

Question 38

describe M6P (mannose-6-phosphate) regarding being a signal for vesicular transport of lysosomal hydrolases to the lysosome/endosome

Answer 38

from the er, there is a lysosomal hydrolase precursor w mannose. there is an additional of phoso-N-acetyl glucosamine (n linked oligosaccharide added in er), the m6p signal is uncovered by loss of N-acetyl-glucosamine == mannose residue phosphorylated thus it becomes m6p in the cgn. then it goes to tgn, m6p receptors here package lysosomal hydrolases, lysosomal hydrolases are released in the late endosome through dissociation at acidic pH and the m6p receptor goes back in retrieval pathway (optional step is the removal of phosphate when it reaches the endosome)