Analysis of Oxysterol Binding Protein Homologue Kes1p Function in Regulation of Sec14p-Dependent Protein Transport from the Yeast Golgi Complex

• Published in: The Journal of cell biology Vol. 157; no. 1; pp. 63 - 77
• Main Authors: Li, Xinmin, Rivas, Marcos P., Fang, Min, Marchena, Jennifer, Mehrotra, Bharat, Chaudhary, Anu, Feng, Li, Prestwich, Glenn D., Bankaitis, Vytas A.
• Format: Journal Article
• Language: English
• Published: United States Rockefeller University Press 01-04-2002; The Rockefeller University Press
• Subjects: 1-Phosphatidylinositol 4-Kinase - genetics; 1-Phosphatidylinositol 4-Kinase - metabolism; ADP-Ribosylation Factor 1 - metabolism; ADP-Ribosylation Factors - genetics; ADP-Ribosylation Factors - metabolism; Alleles; Binding Sites - genetics; Carrier proteins; Carrier Proteins - metabolism; Cells; Cellular biology; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Fungal Proteins - chemistry; Fungal Proteins - genetics; Fungal Proteins - metabolism; Gene expression regulation; Gene Expression Regulation, Fungal; Genetic mutation; Golgi apparatus; Golgi Apparatus - metabolism; GTPase-Activating Proteins - genetics; GTPase-Activating Proteins - metabolism; Lipids; Membrane Proteins - genetics; Molecular Sequence Data; Mutagenesis - physiology; Phosphatidylinositols; Phosphatidylinositols - metabolism; Phospholipid Transfer Proteins; Phosphoric Monoester Hydrolases; Plasmids; Protein Structure, Tertiary; Proteins; Receptors, Steroid - genetics; Saccharomyces cerevisiae Proteins; Sequence Homology, Amino Acid; Truncation; Yeast; Yeasts
• ISSN: 0021-9525; 1540-8140
• DOI: 10.1083/jcb.200201037

Oxysterol binding proteins (OSBPs) comprise a large conserved family of proteins in eukaryotes. Their ubiquity notwithstanding, the functional activities of these proteins remain unknown. Kes1p, one of seven members of the yeast OSBP family, negatively regulates Golgi complex secretory functions that are dependent on the action of the major yeast phosphatidylinositol/phosphatidylcholine Sec14p. We now demonstrate that Kes1p is a peripheral membrane protein of the yeast Golgi complex, that localization to the Golgi complex is required for Kes1p function in vivo, and that targeting of Kes1p to the Golgi complex requires binding to a phosphoinositide pool generated via the action of the Pik1p, but not the Stt4p, PtdIns 4-kinase. Localization of Kes1p to yeast Golgi region also requires function of a conserved motif found in all members of the OSBP family. Finally, we present evidence to suggest that Kes1p may regulate adenosine diphosphate-ribosylation factor (ARF) function in yeast, and that it may be through altered regulation of ARF that Kes1p interfaces with Sec14p in controlling Golgi region secretory function.