Exocytosis

<p>Jun 29, 2014 03:45 PM</p>

<p>

<b>Exocytosis</b> (wiki) = cell directs contents of secretory vesicles OUT of the cell membrane

and into the extracellular space. &nbsp;(Note: above: &nbsp;that process requires 100X more protein

than does ENDOcytosis.) &nbsp;</p>

<p>

Traffricking: &nbsp;likely to use &nbsp;motor proteins and a cytoskeletal track (eg microtubule) to get

closer to target. &nbsp;Actin and MTs involved.</p>

<p>

Tethering: &nbsp;occurs with links of > half the diam of the vesicle &nbsp;(> 25 nm);

=> concetnrates synap vesicles at synapse.</p>

<p>

Docking: &nbsp;precedes formationof &nbsp;SNARE complex, &nbsp;leadingto priming.</p>

<p>

Priming: &nbsp;getting ready for release (after docking but before fusion).

(note: &nbsp;in other cells where secretionis constitutive ie &nbsp;continually occuring and

is calcium independent, and non-triggered, there is no priming.</p>

<p>

Fusion: &nbsp;driven by SNARE proteins.</p>

<p>

&nbsp;

Vesicle Retireval: &nbsp;occurs by endocytosis. &nbsp;can happen after kiss and run.

or &nbsp;may requie complete reformation of vesicles by clathrin.</p>

<p>

Triggered exocytosis and endocytosis are v highly energy dependent and depend on mitochondria.</p>

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&nbsp;</p>