Stephen Fish, Ph'D'

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Stephen Fish, Ph.D. Marshall University J. C. E.
School of Medicine Fish_at_Marshall.edu
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Note to instructors I use these PowerPoint
slides in cell biology lectures that I give to
first year medical students. Copy the slides, or
just the illustrations into your own teaching
media. We all know that teaching science often
requires compromises and simplification for
specific student populations, or the requirements
of a specific course. Please feel free to offer
suggestions for improvements, corrections, or
additional illustrations. I would be pleased to
hear from anyone who finds my work useful, and am
always willing to make it better. Also, the
images have been compressed to screen resolution
to keep PowerPoint file size down, and I can
provide them at any resolution. Stephen E.
Fish, Ph.D.
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Correctly folded proteins are sent to the Golgi
apparatus in vesicles. But first, a little
diversion into vesicle mechanisms
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Vesicle traffic processes that have to be
explained

• How do they form
• How do they fill with cargo molecules
• How do they bud off from the donor compartment
  membrane
• How do they travel to a specific target
  compartment
• How do they fuse with the target membrane

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Vesicle traffic basics
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Loading vesicles with specific molecules
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Click through this sequence for generic coat
formation of vesicles
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Clathrin 3D
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Clathrin assembly in 2D
Clathrin with uncoating ATPase bound (not shown)
Adaptins
Membrane with proteins cargo receptors
Coated pit
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Clathrin assembly in 2D
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Activated ARF Sar1 recruit coat adaptor proteins
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Sherman says
ARF?
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Vesicle removal requires dynamin

• Dynamin several accessory proteins hydrolyze
  GTP to GDP to tighten around the neck of the
  forming vesicle

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Vesicle targeting fusion
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The fusion mechanism

• Rab effector Rab help SNAREs bind
• SNAREs wind up a coiled-coil pull the membranes
  together
• Rab hydrolyzes GTP becomes soluble
• NSF hydrolyzes ATP to disassemble the components
• Fusion can be automatic or triggered by Ca