Sterol transport in yeast and the oxysterol binding protein homologue (OSH) family.
Sterols such as cholesterol are a significant component of eukaryotic cellular membranes, and their unique physical properties influence a wide variety of membrane processes. It is known that the concentration of sterol within the membrane varies widely between organelles, and that the cell actively maintains this distribution through various transport processes. Vesicular pathways such as secretion or endocytosis may account for this traffic, but increasing evidence highlights the importance of nonvesicular routes as well. The structure of an oxysterol-binding protein homologue (OSH) in yeast (Osh4p/Kes1p) has recently been solved, identifying it as a sterol binding protein, and there is evidence consistent with the role of a cytoplasmic, nonvesicular sterol transporter. Yeast have seven such proteins, which appear to have distinct but overlapping functions with regard to maintaining intracellular sterol distribution and homeostasis. Control of sterol distribution can have far-reaching effects on membrane-related functions, and Osh proteins have been implicated in a variety of processes such as secretory vesicle budding from the Golgi and establishment of cell polarity. This review summarizes the current body of knowledge regarding this family and its potential functions, placing it in the context of known and hypothesized pathways of sterol transport in yeast.
Schulz
Timothy A
TA
Laboratory of Cell Biochemistry and Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, US Department of Health and Human Services, Bethesda, MD 20892, USA.
Prinz
William A
WA
D001693:Biological Transport, Active; D002352:Carrier Proteins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000235:genetics / Q000378:metabolism*; D004875:Ergosterol / Q000096:biosynthesis; D006056:Golgi Apparatus / Q000235:genetics / Q000378:metabolism*; D007425:Intracellular Membranes / Q000378:metabolism; D021381:Protein Transport; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D013261:Sterols / Q000378:metabolism*; D033921:Vesicular Transport Proteins / Q000378:metabolism; D000098825:Oxysterol Binding Proteins
D002352:Carrier Proteins; D004875:Ergosterol; D029701:Saccharomyces cerevisiae Proteins; D013261:Sterols; D033921:Vesicular Transport Proteins; C087902:HES1 protein, S cerevisiae; D000098825:Oxysterol Binding Proteins; C432935:OSH2 protein, S cerevisiae; C432936:OSH3 protein, S cerevisiae; C504962:Osh6p protein, S cerevisiae