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Untitled edit
Porosomes vary in size depending on what cell they are on; pancreatic porosomes range from 100nm to 180nm in diameter while in neurons they range from 10nm to 15nm (about 1/10 the size of pancreatic porosomes). When a secretory vesicle containing v-SNARE is located opposite to the porosome containing t-SNARE, membrane continuity (ring complex) is formed between the two. The size of the t/v-SNARE complex is directly proportional to the size of the vesicle. These vesicles contain dehydrated proteins (non-active) which are activated once they are hydrated. Once the vesicle and the porosome form a complex, GTP is needed for active transport through the water channel into the vesicle and to turn on the ion channels. This results in vesicle swelling and an increase in turgor pressure which, in turn, result in the secretion of the contents.
Generally the vesicles are opened and closed by actin, but neurons require a fast response therefore they have central plugs that open to release contents and close to stop the release (the composition of the central plug is yet to be discovered). —Preceding unsigned comment added by 99.30.98.119 (talk) 02:41, 13 October 2009 (UTC)