Mechanisms of Synaptic Vesicle Exocytosis

2/26/01


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Table of Contents

Mechanisms of Synaptic Vesicle Exocytosis

Early Composite drawing of synapse from EM

The Vesicle Cycle

Synaptic Transmission

Exocytosis is the "main" event

Special Needs of Synapses Satisfied

Modern Investigation of the SV Cycle

Small Synaptic Vesicle Cycle

Synaptic Vesicle Membrane and Protein Content

Maturation of a SV

Isolation of Synaptic Vesicles by cell fractionation and centrifugation

Proteins of Synaptic Vesicles are Isolated from Purified Synaptosomes

Step 1: Vesicle filling with NT

EM immunogold to label NX in vesicles

Families of putative trafficking proteins

Step 2: Translocation to PM

Synapsins Translocation?

3 steps of Exocytosis Docking, Priming/Prefusion, Fusion/Exocytosis

Step 3: Synaptic Vesicle Docking

Step 3: Synaptic Vesicle Docking

Step 3: Candidates for Positioning SV at AZ

Synapsins Attachment at AZ?

Mechanisms of Synaptic Vesicle Exocytosis cont.

Small Synaptic Vesicle Cycle

Model - Role of SNAREs in Exocytosis

Step 4: Priming/Prefusion Zipper Model

Structural domains of SNARE Core Complex Proteins

Munc18 "holds" Syntaxin in a closed conformation, preventing core-complex formation

Step 5: Fusion/exocytosis

Calcium Influx During Transmission at the Squid Giant Synapse

How does Calcium Trigger NX Release?

Ca-binding proteins involved in exocytosis

Synaptotagmin - best candidate calcium sensor

Reliable - Unreliability of NX Release

Rab3 regulation of exocytosis

Evidence that Rab3 regulates exocytosis

Recovery of SNARE Core Complex Proteins

Synaptic Transmission

Synthetic Pathway for LDCV

Colocalization of SVs and LDCVs

Glutamate Transport - Anion

Transport of dopamine (similar for other CA) into LDCVs

DA - NA in Chromaffin Granules

Locations of LDCV in CNS

Locations of LDCV

Delay to exocytosis

SVs release at low Hz, LDCVs at High HZ Stimulation

Release of LDCV

LDCV from Tom Sudhof email

Chromaffin (PC12 cells) Model System

Small Synaptic Vesicle Cycle

Evidence for partial release

Evanescent Near Field Microscopy

Evanescent Near Field Microscopy

Zenisek, Steyer, Almers Nature 2000 406:849

Do this whole paper and also some of the recent ones, maybe after Endocytosis

Author: Kristen Harris