Identification and characterization of the human ortholog of rat STXBP1, a protein implicated in vesicle trafficking and neurotransmitter release.
In a screen designed to identify genes expressed preferentially in retina, we identified a cDNA encoding the human ortholog of rat STXBP1 (n-Sec1, Munc-18-1, rbSec1), a protein implicated in vesicle trafficking and neurotransmitter release. This protein also has similarity to Drosophila Rop (65% aa identity) and Caenorhabditis elegans UNC-18 (58% aa identity). The major human cDNA encodes a protein of 594 amino acids which has 100 % amino acid identity with its rat and murine counterparts. Additionally, there is an alternative splice form in humans, arising from the inclusion of an additional exon, which encodes a protein of 603 amino acids and is also 100% identical to the corresponding rat isoform. We found expression of the shorter cDNA in all tissues and cell lines we examined with highest levels in retina and cerebellum. By RT-PCR analysis, we found expression of the longer cDNA in neural tissues only. We mapped the structural gene to 9q34.1, a region without obvious candidate phenotypes. However, due to its evolutionary conservation and abundant expression in retina and brain, STXBP1 should be considered a candidate gene for retinal and/or neural disorders mapping to 9q34.1.
Swanson
D A
DA
Visual Neuroscience Training Program, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
Steel
J M
JM
Valle
D
D
D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000378:metabolism; D017173:Caenorhabditis elegans / Q000235:genetics; D002899:Chromosomes, Human, Pair 9; D018076:DNA, Complementary; D004330:Drosophila / Q000235:genetics; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008969:Molecular Sequence Data; D051938:Munc18 Proteins; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism; D018377:Neurotransmitter Agents / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D051381:Rats; D012160:Retina / Q000378:metabolism; D013572:Synaptic Vesicles / Q000378:metabolism*; D014018:Tissue Distribution; D033921:Vesicular Transport Proteins
D018076:DNA, Complementary; D051938:Munc18 Proteins; D009419:Nerve Tissue Proteins; D018377:Neurotransmitter Agents; C497937:STXBP1 protein, human; C497939:Stxbp1 protein, rat; D033921:Vesicular Transport Proteins