Question

How can it be that complementary pairs of SNAREs uniquely mark veiscles and their target membranes? After vesicle fusion, the target membrane will contain a mixture of t-SNAREs and v-SNAREs. Initially, these SNAREs will be tightly bound to one another, but NSF can pry them apart, reactivating them. What do you suppose prevents target membranes from accumulating a population of v-SNAREs equal to or greater than their population of t-SNAREs?

Answer 1

SNARE are the specific proteins require for vesical fusion to the membrane. v- SNARE present on vesical and t- SNAREs present on target membrane. There will always be some v- SNARE present on target membrane. Immediately after fusion, the v- SNARE will be in inactive complex with t - SNARE. One NSF pries them apart, v- SNARE kept inactive by binding to inhibitory protein. To prevent accumulation of v- SNARE, some retrieval pathway incorporate v- SNARE into vesical for redelivery to original donor membrane. After fusion SNARE returned to orginal membrane via vesical transport. So , once NSF pull apart v and t- SNAREs a vesical formed around v- SNAREs and follow retrograde transport and prevent accumulation of v- SNARE on target membrane.