n-Sec1: a neural-specific syntaxin-binding protein.
We have identified n-Sec1, a rat brain homolog of the yeast Sec1p protein that participates in the constitutive secretory pathway between the Golgi apparatus and the plasma membrane. The rat brain cDNA is predicted to encode a 68-kDa protein with 65% amino acid identity to Drosophila rop, 59% identity to Caenorhabditis elegans unc-18, and 27% identity to Saccharomyces cerevisiae Sec1p. By RNA blot analysis, n-Sec1 mRNA expression is neural-specific. An anti-peptide antiserum directed against the n-Sec1 carboxyl terminus detects a 68-kDa protein in rat brain cytosol and membranes, but not in peripheral tissues. In the presence of syntaxin 1a, a plasma membrane protein implicated in synaptic vesicle docking, n-Sec1 becomes membrane-associated. n-Sec1 binds to syntaxin 1a, 2, and 3 fusion proteins coupled to agarose beads, but not to syntaxin 4 fusion protein or beads coupled to a variety of other proteins. These findings indicate that n-Sec1 is a neural-specific, syntaxin-binding protein that may participate in the regulation of synaptic vesicle docking and fusion.
Pevsner
J
J
Department of Molecular and Cellular Physiology, Howard Hughes Medical Institute, Stanford University Medical Center, CA 94305.
Hsu
S C
SC
Scheller
R H
RH
D000595:Amino Acid Sequence; D000818:Animals; D000954:Antigens, Surface / Q000378:metabolism*; D001483:Base Sequence; D015152:Blotting, Northern; D015153:Blotting, Western; D001923:Brain Chemistry; D002474:Cell-Free System; D003001:Cloning, Molecular; D003600:Cytosol / Q000737:chemistry; D005656:Fungal Proteins / Q000235:genetics* / Q000276:immunology; D008566:Membranes / Q000737:chemistry; D008969:Molecular Sequence Data; D051938:Munc18 Proteins; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism; D011485:Protein Binding; D014176:Protein Biosynthesis; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000276:immunology; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D050827:Syntaxin 1; D014018:Tissue Distribution; D014158:Transcription, Genetic; D033921:Vesicular Transport Proteins
D000954:Antigens, Surface; D005656:Fungal Proteins; D051938:Munc18 Proteins; D009419:Nerve Tissue Proteins; D010446:Peptide Fragments; D011993:Recombinant Fusion Proteins; C494213:Stx1a protein, rat; C497939:Stxbp1 protein, rat; D050827:Syntaxin 1; D033921:Vesicular Transport Proteins