SNIP, a Novel SNAP-25-interacting Protein Implicated in Regulated Exocytosis

• Published in: The Journal of biological chemistry 2000-01, Vol.275 (2), p.1191-1200
• Main Authors: Chin, Lih-Shen, Nugent, Russel D., Raynor, Mathew C., Vavalle, John P., Li, Lian
• Format: Article
• Language: English
• Subjects: Adaptor Proteins, Vesicular Transport; Amino Acid Sequence; Animals; Brain - metabolism; Calcium - metabolism; Carrier Proteins - chemistry; Carrier Proteins - genetics; Carrier Proteins - metabolism; Cloning, Molecular; Exocytosis - physiology; Gene Expression Regulation; Gene Library; Hippocampus - metabolism; Membrane Proteins; Molecular Sequence Data; Molecular Weight; Nerve Tissue Proteins - chemistry; Nerve Tissue Proteins - genetics; Nerve Tissue Proteins - metabolism; Organ Specificity; PC12 Cells; Protein Conformation; Protein Structure, Secondary; Rats; Recombinant Proteins - biosynthesis; Recombinant Proteins - chemistry; SNAP-25 protein; SNIP protein; Subcellular Fractions - metabolism; Synaptosomal-Associated Protein 25; Transfection; Vesicular Transport Proteins
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.275.2.1191

Synaptosome-associated protein of 25 kDa (SNAP-25) is a presynaptic membrane protein that has been clearly implicated in membrane fusion in both developing and mature neurons, although its mechanisms of action are unclear. We have now identified a novel SNAP-25-interacting protein named SNIP. SNIP is a hydrophilic, 145-kDa protein that comprises two predicted coiled-coil domains, two highly charged regions, and two proline-rich domains with multiple PPXY and PXXP motifs. SNIP is selectively expressed in brain where it co-distributes with SNAP-25 in most brain regions. Biochemical studies have revealed that SNIP is tightly associated with the brain cytoskeleton. Subcellular fractionation and immunofluorescence localization studies have demonstrated that SNIP co-localizes with SNAP-25 as well as the cortical actin cytoskeleton, suggesting that SNIP serves as a linker protein connecting SNAP-25 to the submembranous cytoskeleton. By using deletion analysis, we have mapped the binding domains of SNIP and SNAP-25, and we have demonstrated that the SNIP-SNAP-25 association is mediated via coiled-coil interactions. Moreover, we have shown that overexpression of SNIP or its SNAP-25-interacting domain inhibits Ca2+-dependent exocytosis from PC12 cells. These results indicate that SNIP is involved in regulation of neurosecretion, perhaps via its interaction with SNAP-25 and the cytoskeleton.