Vps51p links the VFT complex to the SNARE Tlg1p.
Intracellular membrane fusion requires the complex coordination of SNARE, rab/ypt, and rab effector function. In the yeast Saccharomyces cerevisiae, fusion of endosome-derived vesicles with the late Golgi depends on a cascade of protein-protein interactions that results in the recruitment to Golgi membranes of a conserved docking complex, VFT. This complex binds to Ypt6-GTP, which is necessary for its localization to the Golgi, and also to the SNARE Tlg1p. We show here that the VFT complex contains a fourth, previously uncharacterized, subunit, Vps51p (Ykr020w). Yeast cells lacking VPS51 have defects in vacuole morphology and recycling of the SNARE Snc1p to the plasma membrane, but still assemble a core VFT complex consisting of Vps52p, Vps53p, and Vps54p that localizes properly to the Golgi. Binding to Ypt6-GTP is a property of Vps52p. In contrast, binding to Tlg1p is mediated by a short sequence at the N terminus of Vps51p. Recent evidence suggests that components of a number of rab/ypt effector complexes share a common, distantly related helical coiled-coil motif. We show that each VFT subunit requires this coiled-coil motif for assembly into the complex.
Siniossoglou
Symeon
S
Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, United Kingdom.
Pelham
Hugh R B
HR
D000595:Amino Acid Sequence; D008565:Membrane Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D011485:Protein Binding; D050600:SNARE Proteins; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D033921:Vesicular Transport Proteins
D008565:Membrane Proteins; D050600:SNARE Proteins; D029701:Saccharomyces cerevisiae Proteins; D033921:Vesicular Transport Proteins