Secretory Pathway 2 (Golgi)

Question 1

whats the name of the coat around vesicles going from ER to cis golgi?

Answer 1

COP2

Question 2

whats the name of the coat around vesicles going from cis golgi to ER?

Answer 2

COP1

Question 3

where are cop2 vesicles made?

Answer 3

SER

Question 4

whats the pathway to a cop2 out of the ER?

Answer 4

RER>SER> COP2 vesicles via cytoplasmic tails of membrane proteins>out to cis golgi

Question 5

What is ERGIC?

Answer 5

a receptor that helps certain clotting factors get packed into cop2/helps recruit coat. hemophilia if ERGIC mutation in liver

Question 6

What if certain chaperones and other factors like Bip need to stay in ER? What are 2 ways?

Answer 6

1. are part of larger complexes that don’t diffuse freely into COP2 zones, membrane proteins held by microtubules 2. if get packaged accidentally KDEL sequence gets bound by KDEL receptors in cis golgi and get repackaged back in cop1 to go back to ER

Question 7

What happens at cis cisternae

Answer 7

mannose trimming and synthesis of M6P on lysosomal hydrolases

Question 8

what happens at cis medial

Answer 8

sugars added : N-acetyl glucosamine

Question 9

what happens at trans

Answer 9

Sialic acid (NANA) and galactose, negatively charged

Question 10

What happens at trans golgi network right before protein gets transported out?

Answer 10

furin-mediated cleavage at certain dibasic amino acids, activates certain proteins like

HIV glycoprotein precursor, insulin receptor

Question 11

Where can oligosaccharide-linked sugars be attached to?

What residues do they get attached to?

where does this happen???

Answer 11

glycoproteins and glycolipids…

attached to serine or threonine

The golgi

Question 12

What are the 3 pathways that proteins can go after the golgi?

Answer 12

endosome/lysosome

plasma membrane (constitutive secretory pathway)

secretory granules

Question 13

Explain secretory granule pathway (include explanation of proinsulin cleavage)

Answer 13

stimulation of secretory system..

acidic environemnt drives aggregation of proteins. proinsulin cleaved to insulin bc of acidic, insulin aggregates>maturation of granule

Question 14

Explain the Endosomal/Lysosomal pathway from

ER>cis golgi>trans golgi>TGN>CCV>early endosome

Answer 14

1. ER: N-glycosolation of asp residues via lysosomal hydrolase
2. Cis golgi: GlcNAC phosphotransferase puts 1-phosphate on mannose
3. Trans golgi: remove sugar and uncover m6p signal
4. TGN: m6p binds to m6pR> CCV>fuse w early endosome lower pH causes receptor to be released

Question 15

Elaborate on the constitutive secretory pathway…how can it happen and describe the separate domains of 2 types of polarized cells where it occurs

Answer 15

either directly trans golgi>plasma membrane or indirectly from endosome>plasma

neurons and epithelial cells

epithelial have apical an basolateral membranes

neurons have dendrite and axon membranes

Question 16

Which proteins control vesicle docking? what type of an -ase are they

Answer 16

Rab. GTP-ase. Rab GTP as is part of vesicle and when docks to Rab effector proteins on membranes hydrolyzes.

Question 17

Which rab protein is involved in insulin docking and griscelli syndrome?

Answer 17

Rab 27. secretory pathway issues.

Question 18

What are the complexes that govern vesicle fusion? what are the two types by letter/protein? how many helices?

Answer 18

SNARE complex. V-snare=vesicle snare, synaptobrevin

T-snare, target synaxin

4 helices

Question 19

What are the proteins that bind ca and help form the SNARE complex?

Answer 19

synaptotagmins

Question 20

What can’t break the V complex thats usually used to break down plasma membrane proteins?

Answer 20

SDS

Question 21

What toxin can cleave SNARE to prevent fusion of vesicles?

Answer 21

botox