Vesicular Traffic II

Endocytic and secretory pathways

red = secretorygreen = endocyticblue = recycling

Different coats are used for different transport steps in the cell

Assembly and disassembly of clathrin coat

Dynamin pinches clathrin coated vesicles from the membrane

Electron micrograph from Drosophila mutant

Resting Chemical Synapse

Drosophila mutant can not recycle synaptic vesicles

SNARE proteins guide vesicular transport

Active Chemical Synapse

Interaction of SNARE proteins while docking synaptic vesicle at nerve terminal

Model for membrane fusion. Tight SNARE pairing forces water molecules from areabetween lipid bilayers

Entry of HIV into lymphocytes

Recruitment of cargo molecules into ER transport vesicles

Vesicular tubular clusters move along microtubules to carry proteins from ER to Golgi

apparatus

Vesicular tubular clusters

Microtubules

Microtubules

DVD Clip 58

3-dimensional model of the Golgi Apparatus

Golgi apparatus in an algal cell

ER – Golgi transitional zone in an animal cell

Some enzymes are enriched in cis or trans compartments of the Golgi

substrates specificfor certain enzymes such as acid phosphatase

Functional Compartmentalization of the Golgi Apparatus

Golgi apparatus stained with GFP

Golgi apparatus can be polarly distributedIn this fibroblast Golgi is facing the direction in which

the cell is crawling

Drawing of goblet cell in the intestinal epithelium

Secretes polysacchariderich mucus into thesmall intestine

Golgi is highly polarizedto facilitate release ofmucus throughexocytosis at theapical domain

N-linked glycosylationbecause sugar is addedto N of asparagine.

original precursor oligosaccharide addedto most proteins in the ER

Oligosaccharide chains are processed in the Golgi

common core

complex

high-mannose

Vesicular transport model

Cisternal Maturation Model

Lysosome interior is different from cytosol

Detection of acid phosphatase in lysosomesSmall spheres may be vesicles delivering the

enzyme from the Golgi Apparatus