Disease relevance of Snap23

• METHODOLOGY AND RESULTS: High-efficiency infection of rat pancreatic acini in culture with these adenoviruses by subcellular fractionation showed that the overexpressed SNAP-23, SNAP-25, and their truncated mutant proteins were uniformly targeted to the zymogen granules and plasma membrane [1].
• The clostridial neurotoxin-insensitive soluble N-ethylmaleimide-sensitive factor attachment protein (SNAP) receptors, tetanus neurotoxin-insensitive (TI)-vesicle-associated membrane protein (VAMP)/VAMP7, SNAP23, and syntaxin 3 have recently been implicated in transport of exocytotic vesicles to the apical plasma membrane of epithelial cells [2].

High impact information on Snap23

• Phosphorylation of SNAP-23 regulates exocytosis from mast cells [3].
• We have identified amino acid residues Ser(95) and Ser(120) as the major phosphorylation sites in SNAP-23 in rodent mast cells [3].
• A class of proteins termed SNAREs (including SNAP-23, syntaxins, and VAMPs) are known regulators of secretory granule/plasma membrane fusion events [3].
• These same residues were phosphorylated when mouse platelet degranulation was induced with thrombin, demonstrating that phosphorylation of SNAP-23 Ser(95) and Ser(120) is not restricted to mast cells [3].
• The kinetics of SNAP-23 phosphorylation mirror the kinetics of exocytosis [3].

Biological context of Snap23

• These data suggest that the t-SNAREs SNAP-23 and syntaxin 1 and the v-SNARE cellubrevin participate in general membrane insertion mechanisms involved in diverse glial cell functions such as secretion, phagocytosis, and myelinogenesis [4].
• We emphasize the role of soluble N-ethylmaleimide attachment protein receptors (SNAREs) proteins such as syntaxin 4 that can promote membrane fusion through formation of a stable complex with SNAP-23 [5].

Anatomical context of Snap23

• Quantitative analysis revealed that approximately 10% of SNAP-23 was phosphorylated when mast cell degranulation was induced [3].
• Differential expression of SNAP-25 isoforms and SNAP-23 in the adrenal gland [6].
• Cultured glial cells express the SNAP-25 analogue SNAP-23 [4].
• SNAP-23 and also syntaxin 1 and cellubrevin were found to be expressed in glial precursor cells, oligodendrocytes, and microglia [4].
• By using immunocytochemical, immunoblotting, and polymerase chain reaction techniques, the present study demonstrates that SNAP-23, an analogue of SNAP-25, is expressed by astrocytes both in culture and in rat cerebellum [4].

Associations of Snap23 with chemical compounds

• A peptide derived from the N-terminus of syntaxin 2 or the C-terminus of SNAP-23 significantly inhibited Ca(2+)- and GTPgammaS-stimulated surfactant secretion from permeabilized type II cells in a dose-dependent manner [7].
• Both SNAP-23 and SNAP-25 associate with the plasma membrane and can be metabolically labeled with [(3)H] palmitate in AtT-20 cells [8].
• Syntaxin 2, SNAP-23, and annexin A2 co-localized with the CD44 clusters, which were cholesterol dependent [9].

Physical interactions of Snap23

• Associated kinase activity, which diminishes after stimulation as a consequence of intracellular calcium increases, specifically phosphorylates syntaxin 4 thereby affecting its capacity to bind to its t-SNARE partner SNAP-23 [5].

Regulatory relationships of Snap23

• Cholecystokinin-regulated exocytosis in rat pancreatic acinar cells is inhibited by a C-terminus truncated mutant of SNAP-23 [1].

Other interactions of Snap23

• In the pancreatic acinar cell, synaptosomal-associated protein of 23 kd (SNAP-23) is the major SNAP-25 isoform expressed in pancreatic acinar cells, but its role in acinar cell exocytosis has not been determined [1].
• Immunoblotting analysis showed that parotid acini contain both syntaxin-4 and SNAP-23, plausible candidates of target membranes (t-) SNAREs in non-neuronal cells [10].
• Contrary to results from in vitro binding assays, SNAP-23 was found predominantly associated with syntaxin 3 [8].
• SNAREs were found either excluded (syntaxin2), equally distributed between raft and non-raft fractions (syntaxin4, VAMP-8, VAMP-2), or selectively enriched in rafts (syntaxin3, SNAP-23) [11].
• Cognate SNARE complexes of syntaxin3 with SNAP-23 and VAMP-8 were enriched in rafts, whereas Munc18-2/syntaxin3 complexes were excluded [11].

Analytical, diagnostic and therapeutic context of Snap23

• Southern blot analysis reveals that the rat, mouse and human SNAP-23 genes encode species-specific isoforms of the same protein [12].
• Expression of SNAP-25 isoforms and SNAP-23 was examined by immunoblotting, immunofluorescence, and RT-PCR [6].
• Further immunohistochemistry and fractionation studies show that while SNAP-25 is enriched in axons and nerve terminals, SNAP-23 is concentrated in cell bodies [8].
• Among these, the identities of SNAP 23, apolipoprotein A-1 and E, clusterin, kinesin, and fibrinogen gamma were confirmed by Western blot assay, and apo E was further analyzed by using 2-DE immunoblot assays to determine isoform patterns [13].

References