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Mol Biol Cell

Title:		Multiple functions of sterols in yeast endocytosis
Author(s):		Heese-Peck A; Pichler H; Zanolari B; Watanabe R; Daum G; Riezman H;
Address:		"Biozentrum, University of Basel, Switzerland"
Journal Title:		Mol Biol Cell
Year:		2002
Volume:		13
Issue:		8
Page Number:		2664 - 2680
DOI:		10.1091/mbc.e02-04-0186
ISSN/ISBN:		1059-1524 (Print) 1059-1524 (Linking)
Abstract:		"Sterols are essential factors for endocytosis in animals and yeast. To investigate the sterol structural requirements for yeast endocytosis, we created a variety of ergDelta mutants, each accumulating a distinct set of sterols different from ergosterol. Mutant erg2Deltaerg6Delta and erg3Deltaerg6Delta cells exhibit a strong internalization defect of the alpha-factor receptor (Ste2p). Specific sterol structures are necessary for pheromone-dependent receptor hyperphosphorylation, a prerequisite for internalization. The lack of phosphorylation is not due to a defect in Ste2p localization or in ligand-receptor interaction. Contrary to most known endocytic factors, sterols seem to function in internalization independently of actin. Furthermore, sterol structures are required at a postinternalization step of endocytosis. ergDelta cells were able to take up the membrane marker FM4-64, but exhibited defects in FM4-64 movement through endosomal compartments to the vacuole. Therefore, there are at least two roles for sterols in endocytosis. Based on sterol analysis, the sterol structural requirements for these two processes were different, suggesting that sterols may have distinct functions at different places in the endocytic pathway. Interestingly, sterol structures unable to support endocytosis allowed transport of the glycosylphosphatidylinositol-anchored protein Gas1p from the endoplasmic reticulum to Golgi compartment"
Keywords:		"Actins/metabolism Animals Cytoskeleton/metabolism Endocytosis/*physiology Molecular Structure Phosphorylation Protein Binding Receptors, Mating Factor Receptors, Peptide/metabolism Steroid Isomerases/genetics/metabolism Sterols/chemistry/*metabolism *Tran;"
Notes:		"MedlineHeese-Peck, Antje Pichler, Harald Zanolari, Bettina Watanabe, Reika Daum, Gunther Riezman, Howard eng Research Support, Non-U.S. Gov't 2002/08/16 Mol Biol Cell. 2002 Aug; 13(8):2664-80. doi: 10.1091/mbc.e02-04-0186"