Sgf1p, a New Component of the Sec34p/Sec35p Complex |
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Authors: | Dong-Wook Kim Thomas Massey Michael Sacher Marc Pypaert Susan Ferro-Novick |
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Institution: | Department of Cell Biology and;Howard Hughes Medical Institute, Yale University, New Haven, CT, USA |
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Abstract: | 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. |
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Keywords: | membrane traffic secretion vesicle tethering |
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