SNIP, a novel SNAP-25-interacting protein implicated in regulated exocytosis.
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 Ca(2+)-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.
Chin
L S
LS
Departments of Pharmacology and Physiology, Bowles Center for Alcohol Studies, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599, USA.
Nugent
R D
RD
Raynor
M C
MC
Vavalle
J P
JP
Li
L
L
D033942:Adaptor Proteins, Vesicular Transport; D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D005089:Exocytosis / Q000502:physiology*; D005786:Gene Expression Regulation; D015723:Gene Library; D006624:Hippocampus / Q000378:metabolism; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D009928:Organ Specificity; D016716:PC12 Cells; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D051381:Rats; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry; D013347:Subcellular Fractions / Q000378:metabolism; D050825:Synaptosomal-Associated Protein 25; D014162:Transfection; D033921:Vesicular Transport Proteins
D033942:Adaptor Proteins, Vesicular Transport; D002352:Carrier Proteins; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D011994:Recombinant Proteins; C494210:Snap25 protein, rat; C000631270:Srcin1 protein, rat; D050825:Synaptosomal-Associated Protein 25; D033921:Vesicular Transport Proteins; D002118:Calcium