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Sgf1p, a New Component of the Sec34p/Sec35p Complex
Author(s) -
Kim DongWook,
Massey Thomas,
Sacher Michael,
Pypaert Marc,
FerroNovick Susan
Publication year - 2001
Publication title -
traffic
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.677
H-Index - 130
eISSN - 1600-0854
pISSN - 1398-9219
DOI - 10.1034/j.1600-0854.2001.21111.x
Subject(s) - golgi apparatus , biology , endoplasmic reticulum , copi , secretion , microbiology and biotechnology , protein subunit , copii , secretory pathway , mutant , multiprotein complex , brefeldin a , secretory protein , biochemistry , gene
Here we report the identification of SGF1 as a high‐copy suppressor of the sec35–1 mutant. SGF1 encodes an essential hydrophilic protein of ∼ 100 kDa. Using the yeast two‐hybrid system and coprecipitation studies, we demonstrate that Sgf1p is a new subunit of the multiprotein Sec34p/Sec35p complex. Reduced levels of Sgf1p lead to the accumulation of a variety of membranes as well as a kinetic block in endoplasmic reticulum to Golgi traffic. Immunofluorescence studies demonstrate that Sec34p is found throughout the Golgi, with a high concentration on early Golgi. Although an earlier study suggested that Sec34p (Grd20p) is not required for protein secretion, we show here that the sec34–2 and sec35–1 mutations lead to a pleiotropic block in the secretion of all proteins into the growth medium.