A SNARE-LIKE PROTEIN REQUIRED FOR TRAFFIC THROUGH THE GOLGI-COMPLEX

THE secretory pathway of eukaryotic cells comprises several distinct m embrane-bound compartments which are interconnected by transport vesic les that pinch off from one membrane and fuse with the next. Targeting of these vesicles is mediated in part by interactions between integra l membrane proteins on the vesicles and target organelles (soluble NSF attachment protein receptors (SNAREs)), termed v-SNAREs and t-SNAREs, respectively(1-4). SNAREs required for endoplasmic reticulum (ER)-Gol gi transport and for fusion of vesicles with the plasma membrane are a lready known. Here we identify two yeast membrane proteins that show g enetic interactions with Sed5p, which is the t-SNARE for ER-Golgi traf fic(3,4). One of these membrane proteins, Sft1p, is structurally simil ar to the known v-SNAREs and is required for transport from an early t o a later Golgi compartment. Our results indicate that a single t-SNAR E can control more than one transport step, and provide the first cand idate for a SNARE involved in intra-Golgi traffic.