SNARE proteins (Soluble N-ethymaleimide- sensitive –factor attachment proteins) are transmembrane proteins that are involved in the catalysis of membrane fusion events within the cell by bringing together cell membranes and organelle membranes. This process allows for efficient transport of substances within membrane vesicles to their correct final location in the cell.
SNAREs are present in organelle membranes and vesicles, there ar two types of SNARE protein, v-SNARE ( vesicle SNARE) and t-SNARE (target membrane SNARE). They exist in complementary pairs of a t-SNARE atttched to the membrane of the target organelle and a v-SNARE on the membrane of the vesicle to be released. The specific v-SNARE on the vesicle recognises the correct t-SNARE and binds to it; in doing so the vesicle is directed to its correct location in the cell. SNARES provide an “extra layer of specificity” to ensure efficient intracellular trafficking.
Once the SNAREs are bound to each other a SNARE complex is formed in which the helical domains of the t and v SNAREs anchor the vesicle and the Plasma membrane together. The v-SNARE consists of just one protein where as the t-SNARE consists of two or three and it is these proteins which bind together to form the four helix bundle to faclitate Exocytosis