The Yip1p.Yif1p complex is required for the fusion competence of endoplasmic reticulum-derived vesicles.
Here we report that Yip1p and Yif1p, two members of an integral membrane protein complex that bind to the Rab Ypt1p, are required for membrane fusion with the Golgi in vitro. To block fusion, anti-Yip1p or anti-Yif1p antibodies must be added before vesicles bud from the endoplasmic reticulum (ER). These antibodies do not block the packaging of Yip1p, Yif1p, or the soluble NSF attachment protein receptor (SNAREs) into vesicles. We propose that Yip1p and Yif1p perform a critical role in establishing the fusion competence of ER to Golgi vesicles at the time of budding. Consistent with this proposal, we observe that the Yip1p.Yif1p complex binds to the ER to Golgi SNAREs Bos1p and Sec22p, two components of the membrane fusion machinery.
Barrowman
Jemima
J
Howard Hughes Medical Institute and the Department of Cell Biology, Yale University School of Medicine, New Haven, Connecticut 06519, USA.
Wang
Wei
W
Zhang
Yueyi
Y
Ferro-Novick
Susan
S
D033942:Adaptor Proteins, Vesicular Transport; D000818:Animals; D000906:Antibodies / Q000276:immunology; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D005656:Fungal Proteins / Q000276:immunology / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism; D008561:Membrane Fusion / Q000276:immunology; D008565:Membrane Proteins; D011817:Rabbits; D029701:Saccharomyces cerevisiae Proteins / Q000276:immunology / Q000378:metabolism*; D033921:Vesicular Transport Proteins
D033942:Adaptor Proteins, Vesicular Transport; D000906:Antibodies; D005656:Fungal Proteins; D008565:Membrane Proteins; D029701:Saccharomyces cerevisiae Proteins; D033921:Vesicular Transport Proteins; C473803:YIF1 protein, S cerevisiae; C414462:Yip1 protein, S cerevisiae