BIO 320 Study Guide - Midterm Guide: Dynamin, Signal Transducing Adaptor Protein, Copii
Exam 2 Vocabulary Review
Coated Vesicles (Lecture 5)
1. Sar1
a. GTPase that recruits coat proteins and also causes membrane curvature (even without
COPII)
b. Hydrolyzes GTP to start COPII uncoating process
2. Sec23 and Sec24
a. Are recruited by Sar1 and binds to cargo protein receptors
3. Clathrin
a. Vesicles go from endosomes to lysosomes (used with M6P)
4. Adaptor protein (Ap2)
a. Adaptor protein for clathrin; similar to inner COPII proteins
5. Dynamin
a. Helps pinch off clathrin coat
6. COPI
a. Used for retrograde transport
7. COPII
a. Used for anterograde transport
8. Rab1
a. GTP complex on ER and Golgi complex, helps identify target membrane
b. Can bind to SNARE inhibitor on t-SNARE to release it
c. Dissociates from effector protein, GDI and has conformational change when it comes
into contact with GEF
9. C20 groups
a. Modified cysteine groups of Rab1 near its C terminus
10. GDI
a. Keeps Rab1 soluble in cytosol
b. When dissociates from Rab1, C20 groups anchor Rab1 to the lipid membrane
11. Tethering proteins
a. Binds to Rab1 and pulls vesicle toward target membrane (Rab effector)
b. Phosphorylates COPII coat proteins to finish uncoating process
12. SNAREs
a. Provides specificity for vesicle targeting
b. Drives process of membrane fusion
c. Required ALONG WITH RAB proteins for specific and efficient membrane fusing
d. V and T SNAREs that work in specific combinations 4 helix bundle/trans-SNARE
complex more stable/requires no energy
13. NSF
a. Protein + accessory signaling proteins
b. Uses ATP hydrolysis to unravel SNARE complexes so SNAREs can be reused
14. Snap25
a. Form of t-SNARE that gets broken down by botox, which prevents neurotransmitter
acetylcholine and prevents muscle contractions/wrinkles
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Traffic From and Within the Golgi (Lecture 6)
15. Endoplasmic reticulum
a. Most proteins come here to get N-linked glycosylated and undergo glucose trimming; all
proteins that come here get folded (only properly folded proteins leave, others try to
get fixed and/or degraded)
16. Vesicular tubular cluster (VTC)
a. Transport vesicles from the ER that fuse together to become the cis-Golgi network
(CGN)
17. Golgi apparatus
a. Different enzymes define the different sub-compartments
b. Goes from cis to trans
c. Some proteins get O-glycosylated (proteins can be both N and O-glycosylated)
18. Cisternal maturation model
a. Uses retrograde trasport to oe residet proteis fro tras to is diretio ad
change identities of the sub-compartments
b. Model of Golgi apparatus that shows the resident proteins moving backward and
decreasing the size of the trans-Golgi network over time; later compartment becomes
earlier compartment
i. (wrong model shows the vesicular proteins moving from compartment to
compartment)
19. N-linked glycosylation
a. Big block of sugar molecules added on at once (to an asparagine)
b. Happens in ER, but can be further modified in the Golgi (gets trimmed and then other
carbohydrates are added on; heterogeneity from resulting different masses serves as
like a stamp as to how far the protein got in the Golgi)
20. O-linked glycosylation
a. Sugar molecules are added on one at a time (to a threonine or serine)
b. Happens in the ER
21. Congenital disorder of glycosylation (CDG syndrome)
a. Rare birth defect that leads to different organ malfunctions
22. Protein glycosylation
a. Folding/misfolded retention
b. Restricts access/prevents degradation
c. Cell recognition
d. Special roles
23. Anterograde traffic
a. ER Golgi plasma membrane/destination
24. Retrograde traffic
a. Golgi ER
b. Used in cisternal maturation model
c. Maintains ER surface area
d. Brings back membrane proteins and certain soluble luminal proteins
25. Bip
a. Soluble molecule chaperone that helps proteins fold
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b. Needs to stay concentrated in ER
26. PDI (protein disulfide isomerase)
a. Soluble ER resident protein
b. Also needs to stay concentrated in ER
27. KDEL sequence
a. Must be at very C-terminus end (lysine/K, asparagine/D, glutamine/E, and leucine/L; all
acidic)
i. (alternative in all basic: histidine, glutamine, and asparagine (HED))
b. Both sufficient and necessary for protein retrieval
c. Sufficiency proven by removing KDEL sequence, necessity proven by adding on
d. Brings proteins back from VTC or Golgi
e. Higher affinity at acidic pH, so protein dissociates from receptor back in neutral ER
lumen
28. Gradual acidification
a. ER Golgi, pH goes from neutral acidic
b. Affects binding in both anterograde and retrograde transport
29. Retention
a. In ER lumen, proteins can associate with each other to increase retention
30. Retrieval
a. Mechanism used by KDEL receptors
31. KKXX signal
a. On very C-terminal end (Lysine-lysine-anything-anything)
b. Membrane proteins bind directly to COPI coat proteins and uses this to bind to COPI
32. Constitutive secretory pathway
a. Default, happens all the time
33. Regulated secretory pathway
a. Happens for proteins with special features
34. Proteasomes
a. Destroys only poly-ubiquinated proteins
35. Lysosomes
a. Contains hydrolytic enzymes (hydrolases) for destruction; broken down products get
returned to the cytosol
b. Cell protected from hydrolases by the membrane, final proteolytic cleavage of
hydrolases for optimal activity, low optimal pH about 5.0 (maintained by ATP-
hydrolyzed proton pump)
c. Components of lysosome protected against hydrolases by heavy glycosylation
36. GlcNAc phosphotransferase
a. Adds on GlcNAc phosphate in CGN to one or two mannose of N-linked glycosylated
protei that’s ee tried in the ER
37. Mannose 6-phosphate (M6P)
a. Results from removal of Glc-NA, hih leaes ol a phosphate o the aose’s 6th
position
b. Signal for delivering hydrolases to endosomes than to the lysosomes
c. Not used for proteins going to the plasma membrane
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