GS15, a 15-kilodalton Golgi soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) homologous to rbet1.

Bet1p plays an essential role in vesicular transport from the endoplasmic reticulum (ER) to the Golgi in yeast, and it functions as a vesicle soluble N-ethylmaleimide-sensitive factor protein receptor (v-SNARE). A mammalian protein related to Bet1p has been reported previously and was referred to as rbet1. We have now identified a new mammalian protein that is homologous to rbet1 (28% amino acid identity). mRNA for this rbet1 homologue is widely expressed in rat tissues. Affinity-purified polyclonal antibodies raised against recombinant protein specifically recognized a 15-kilodalton integral membrane protein highly enriched in Golgi membranes. Indirect immunofluorescence microscopy revealed that this protein is specifically associated with the Golgi apparatus in diverse cell types. Biochemical characterization established that this protein behaves like a SNARE and was named GS15 (Golgi SNARE with a size of 15 kilodaltons). These properties raise the possibility that GS15 is a novel SNARE mediating a yet to be defined transport event associated with the Golgi apparatus.