SNAP23

Synaptosomal-associated protein 23 is a is_associated_with::protein that in humans is encoded by the SNAP23 is_associated_with::gene. Two alternative transcript variants encoding different protein isoforms have been described for this gene.

Function
Specificity of vesicular transport is regulated, in part, by the interaction of a is_associated_with::vesicle-associated membrane protein termed is_associated_with::synaptobrevin/VAMP with a target compartment membrane protein termed is_associated_with::syntaxin. These proteins, together with is_associated_with::SNAP25 (synaptosome-associated protein of 25 kDa), form a complex which serves as a binding site for the general membrane fusion machinery. Synaptobrevin/VAMP and syntaxin are believed to be involved in vesicular transport in most, if not all cells, while SNAP25 is present almost exclusively in the brain, suggesting that a ubiquitously expressed homolog of SNAP25 exists to facilitate transport vesicle/target membrane fusion in other tissues.

SNAP23 is structurally and functionally similar to SNAP25 and binds tightly to multiple syntaxins and synaptobrevins/VAMPs. It is an essential component of the high affinity receptor for the general membrane fusion machinery and is an important regulator of transport vesicle docking and fusion.

Clinical significance
In individuals with is_associated_with::insulin resistance, SNAP23 is found to be translocated from the plasma membrane to the cytosol where it becomes associated with lipid droplets and is therefore unable to translocate GLUT-4 to the membrane, hindering glucose transport.

Interactions
SNAP23 has been shown to interact with is_associated_with::STX2,   NAPA, is_associated_with::KIF5B, is_associated_with::STX6, is_associated_with::SYBL1,  is_associated_with::VAMP2,  is_associated_with::Cystic fibrosis transmembrane conductance regulator, is_associated_with::STX4,       is_associated_with::Syntaxin 3,    is_associated_with::STX1A,     is_associated_with::Vesicle-associated membrane protein 8,  is_associated_with::STX11, is_associated_with::VAMP3   and is_associated_with::SNAPAP.