GS15, A 15-KILODALTON GOLGI SOLUBLE N-ETHYLMALEIMIDE-SENSITIVE FACTORATTACHMENT PROTEIN-RECEPTOR (SNARE) HOMOLOGOUS TO RBET1

Bet1p plays an essential role in vesicular transport from the endoplas mic reticulum (ER) to the Golgi in yeast, and it functions as a vesicl e soluble N-ethylmaleimide-sensitive factor protein receptor (V-SNARE) . A mammalian protein related to Bet1p has been reported. previously a nd was referred to as rbet1. Pie have now identified a new mammalian p rotein that is homologous to rbet1 (28% amino acid identity). mRNA for this rbet1 homologue is widely expressed in rat tissues. Affinity pur ified polyclonal antibodies raised against recombinant protein specifi cally recognized a <(15)under bar>-kilodalton integral membrane protei n highly enriched in Golgi membranes. Indirect immunofluorescence micr oscopy revealed that this protein is specifically associated with the Golgi apparatus in diverse cell types. Biochemical characterization es tablished that this protein behaves like a SNARE and was named GS15 (G olgi SNARE with a size of 15 kilodaltons). These properties raise the possibility that GS15 is a novel SNARE mediating a yet to be defined t ransport event associated with the Golgi apparatus.