Siniossoglou Symeon, Pelham Hugh R B
Medical Research Council Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, United Kingdom.
J Biol Chem. 2002 Dec 13;277(50):48318-24. doi: 10.1074/jbc.M209428200. Epub 2002 Oct 10.
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.
细胞内膜融合需要SNARE、rab/ypt和rab效应器功能的复杂协调。在酿酒酵母中，内体来源的囊泡与晚期高尔基体的融合依赖于一系列蛋白质-蛋白质相互作用，这些相互作用导致一种保守的对接复合物VFT被招募到高尔基体膜上。该复合物与Ypt6-GTP结合，这是其定位于高尔基体所必需的，同时也与SNARE Tlg1p结合。我们在此表明，VFT复合物包含第四个以前未被鉴定的亚基Vps51p（Ykr020w）。缺乏VPS51的酵母细胞在液泡形态和SNARE Snc1p向质膜的循环方面存在缺陷，但仍能组装由Vps52p、Vps53p和Vps54p组成的核心VFT复合物，该复合物能正确定位于高尔基体。与Ypt6-GTP结合是Vps52p的特性。相反，与Tlg1p的结合是由Vps51p N端的一个短序列介导的。最近的证据表明，许多rab/ypt效应器复合物的组分共享一个共同的、远缘相关的螺旋卷曲螺旋基序。我们表明，每个VFT亚基都需要这个卷曲螺旋基序才能组装到复合物中。
