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Vesicular Traffickin
Vesicular Trafficking
Question | Answer |
---|---|
Describe cargo specific endocytosis | There are specific receptors for ligands to bind. Conformation change foor adaptin to bind. Clathrin binds and vesicle is separated from PM. Cell uncoats |
Describe non-specific endocytosis | Does not require specific receptor. SAR in the RER. A coat can form around vesicle (not clathrin) Whatever happens to be around will be in vesicle |
What are the 2 conformations SAR can exist as? | SAR-GTP and SAR GDP |
Describe SAR GTP. SAR GDP | SAR has fatty acid tail out. SAR GDP has tail buried |
What causes transformation of SAR GTP to SAR GDP? | GTPase activity in the SAR small G-protein has to be activated. GAP (GTP activating protein) hydrolyses GTP to GDP |
How do you convert SAR GDP to GTP? | GEP(GTP exchanging protein) |
How is the vesicle uncoated using SAR GAP? | SAR GAP is activated when the vesicle forms and it goes to GDP form and the tail retracts and the SAR falls off |
SAR in the RER is analogous to what in the Golgi? | ARF |
How does RAB participate in targeting vesicles? | RAB is a small G protein. There are RAB effectors in the kinesin/dynesin complex. Need RAB to know where to go. |
What 2 forms does RAB exist in? | RAB GTP and RAB GDP (Similar pathway as SAR) |
Is RAB the only protein needed in vesicle targeting? | No, Need SNARE. A V-SNARE and T-SNARE |
True or False. RAB effector and T-SNARE are located on the vesicular membrane | False. They are located on the target protein |
Where is teh RAB and V-SNARE located? | On the vesicle |
After RAB is released and recycled what happens to the vesicle? | It fuses with the target membrane. |
About how many SNAREs are on the vesicles? | 40-60 SNAREs |
What role does NSF play a role in vesicular fusion? | It is an enzyme complex that will unwind SNAREs to be recycled. NSF is a chaperone |
True or False. Proteins in the plasma membrane will have longer transmembrane region than ones in the RER | True. Because the membrane is getting thicker and thicker |
When are neurotransmitters released? | When the vesicle fuses. Neurotransmitters are regulated by electrical signaling that will tell by depolarization of the membrane |
Describe the role of synaptotagmin | Regulatory protein that binds to SNARE complex acting as a brake. It inhibits the process of winding of the SNAREs |
How is synaptotagmin released from the SNARE? | After depolarization calcium rushes in and binds to synapatotagmin |
How is insulin a regulated secretion? | Insulin is released only when glucose is high. Glucose causes ATP to rise an K+ channels binds the ATP so it can open causing depolarization. Ca2+ channels open and binds to synaptotagmin |