SNAP23

SNAP-23 (synaptosomal-associated protein 23) is a member of the SNAP family of SNARE proteins found in vertebrates. The protein is encoded by the human SNAP23 gene and has a molecular weight of about 23 kDa. SNAP-23 is anchored to the plasma membrane by lipid modification in a cysteine-rich region, enabling it to participate in membrane fusion events.

Function: SNAP-23 is a t-SNARE that participates in the formation of SNARE complexes with other plasma-membrane SNAREs, such as syntaxin-4 and VAMP-2 or VAMP-3. These complexes drive the fusion of secretory vesicles with the plasma membrane, a central step in regulated exocytosis. In non-neuronal cells, SNAP-23 mediates diverse secretory processes, including insulin-stimulated GLUT4 vesicle fusion in adipocytes and hormone or cytokine release in epithelial and immune cells. In platelets, SNAP-23 participates in granule secretion during activation.

Regulation: The activity and membrane association of SNAP-23 are regulated by post-translational modifications. Palmitoylation anchors SNAP-23 to the plasma membrane, while protein kinase C–mediated phosphorylation at specific serine residues modulates SNARE complex assembly and exocytic efficiency.

Interacting partners and localization: SNAP-23 interacts with syntaxin-4 and VAMP family proteins to form functional SNARE complexes at the plasma membrane. It is broadly expressed in non-neuronal tissues, with localization primarily at the inner plasma membrane.

Clinical relevance: Given its central role in regulated secretion, SNAP-23 function has been studied in contexts such as metabolic regulation of glucose uptake and platelet activation. Alterations in SNAP-23–dependent exocytosis can affect secretory capacity in several cell types.

See also: SNARE proteins, syntaxin-4, VAMP-2, VAMP-3, GLUT4 trafficking.