Three novel proteins of the syntaxin/SNAP-25 family

Intracellular membrane traffic is thought to be regulated in part by solubl e N-ethylmaleimide-sensitive factor-attachment protein receptors (SNAREs) t hrough the formation of complexes between these proteins present on vesicle and target membranes. All known SNARE-mediated fusion events involve membe rs of the syntaxin and vesicle-associated membrane protein families, The di versity of mammalian membrane compartments predicts the existence of a larg e number of different syntaxin and vesicle-associated membrane protein geen es. To further investigate the spectrum of SNAREs and their roles in membra ne trafficking we characterized three novel members of the syntaxin and SNA P-25 (synaptosome-associated protein of 25 kDa) subfamilies, The proteins a re broadly expressed, suggesting at general role in vesicle trafficking, an d localize to distinct membrane compartments. Syntaxin 8 co-localizes with markers of the endoplasmic reticulum, Syntaxin 17, a divergent member of th e syntaxin family, partially overlaps with endoplasmic reticulum markers, a nd SNAP-29 is broadly localized on multiple membranes, SNAP-29 does not con tain a predicted membrane anchor characteristic of other SNAREs. In vitro s tudies established that SNAP-29 is capable of binding to a broad range of s yntaxins.