Synaptic transmission II

Question 1

Vesicle fusion (2 types of events)

Answer 1

• First: transport vesicle must recognize the correct target membrane
• Second: vesicle and target must fuse.

Question 2

The SNARE hypothesis describes via the interaction between specific pairs of transmembrane proteins, called _____, on the vesicel (_________) and the target membrane (_________), respectively.

Answer 2

1. SNARES
2. v-SNAREs
3. t-SNAREs

Question 3

Proteins involved in synaptic release are?

Answer 3

1. Restrain vesicles
2. Target vesicles to active zone
3. Dock vesicles to active zone
4. Allow fusion/exocytosis
5. Retrieve fused membrane (recycling)

Question 4

SNAp Receptors are?

Answer 4

Group of proteins that promote fusion of the vesicles and presynaptic membrane

Question 5

Synapsin tethers vesicles to the cytoskeleton. _______phosphorylates Synapsin to mobilize the Reserve pool

Answer 5

CaMKII

Question 6

Exocytosis - the SNARE hypothesis (Proteins involved)

Answer 6

-V-SNARE (vesicle-SNARE)
  Synaptobrevin (or VAMP 
-T-SNAREs (target-SNARE) 
  Syntaxin / SNAP25 
-Synaptotagmin (calcium sensor)
-Neurexins (interact with synaptotagmin)

Question 7

Exocytosis - the SNARE hypothesis (Proteins involved)

Answer 7

• N-ethylmaleimide sensitive factor (NSF) and α-SNAP (soluble NSF attachment protein):
• *responsible for priming: bind SNARE, utilizes ATP to break apart complexes after fusion
• munc-18—binds with syntaxin to inhibit SNARE complex formation

Question 8

Synaptobrevin

Answer 8

Sits in the vesicle membrane (V-SNARE)

Question 9

Syntaxin and SNAP-25 are anchored in the ?

Answer 9

Presynaptic membrane (T-SNAREs)

Question 10

Synapsins

Answer 10

• Cytoskeletal filaments
• Regulated by cAMP-dependent kinase and Ca2+/calmodulin dependent kinase
• Phosphorylation frees vesicles to move.

Question 11

Rab Proteins

Answer 11

Ras superfamily of G-proteins

Question 12

Calcium Sensor –Synaptotagmin-1

Answer 12

• Has two C2 domains related to PKC
• calcium sensor
• Also aids in recycling (binds clathrin)

Question 13

Endocytosis

Clathrin and dynamin?

Answer 13

Clathrin- forms coated pits

Dynamin-Pinches of coated vesicle

Question 14

direction of PSP is determined by?

Answer 14

• Ionic identity
• Equilibrium or reversal potential
• *EPSP= more positive than AP threshold
• *IPSP= more negative then threshold

Question 15

Excitatory input (one example)

Answer 15

• Glutamate

- Permeable to Na+ and K+

Question 16

Inhibitory input (One example)

Answer 16

• GABA

- Permeable to Cl-

Question 17

Synaptic inhibition does what?

Answer 17

• Reduces probability of AP
• GABA or glycine open chloride channels (hyperpolarization)
• Can be depolarizing and inhibitory as long as the ECl- is more hyperpolarized (negative) than the action potential threshold (C).

Question 18

Shunting inhibition

Answer 18

increase in “resting” conductance

• *: If ECl- is equal to RMP, opening of Cl- channels does not hyperpolarize the cell, yet will act inhibitory on simultaneous EPSPs
• *Opening of Cl- channels increases membrane conductance (reduces resistance)

Question 19

Shunting inhibition

Answer 19

No potential (but conductance) change
(if ECl- = RMP) shunting inhibition
*Hyperpolarization (if ECl- more negative than RMP