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Mol Biol Cell

Title:		Visualization of receptor-mediated endocytosis in yeast
Author(s):		Mulholland J; Konopka J; Singer-Kruger B; Zerial M; Botstein D;
Address:		"Department of Genetics, Stanford University School of Medicine, Stanford, California 94305-5120, USA"
Journal Title:		Mol Biol Cell
Year:		1999
Volume:		10
Issue:		3
Page Number:		799 - 817
DOI:		10.1091/mbc.10.3.799
ISSN/ISBN:		1059-1524 (Print) 1059-1524 (Linking)
Abstract:		"We studied the ligand-induced endocytosis of the yeast alpha-factor receptor Ste2p by immuno-electron microscopy. We observed and quantitated time-dependent loss of Ste2p from the plasma membrane of cells exposed to alpha-factor. This ligand-induced internalization of Ste2p was blocked in the well-characterized endocytosis-deficient mutant sac6Delta. We provide evidence that implicates furrow-like invaginations of the plasma membrane as the site of receptor internalization. These invaginations are distinct from the finger-like plasma membrane invaginations within actin cortical patches. Consistent with this, we show that Ste2p is not located within the cortical actin patch before and during receptor-mediated endocytosis. In wild-type cells exposed to alpha-factor we also observed and quantitated a time-dependent accumulation of Ste2p in intracellular, membrane-bound compartments. These compartments have a characteristic electron density but variable shape and size and are often located adjacent to the vacuole. In immuno-electron microscopy experiments these compartments labeled with antibodies directed against the rab5 homologue Ypt51p (Vps21p), the resident vacuolar protease carboxypeptidase Y, and the vacuolar H+-ATPase Vph1p. Using a new double-labeling technique we have colocalized antibodies against Ste2p and carboxypeptidase Y to this compartment, thereby identifying these compartments as prevacuolar late endosomes"
Keywords:		"Actins/metabolism/ultrastructure Biological Transport Cell Compartmentation Cell Membrane/ultrastructure Endocytosis/drug effects/*physiology Endosomes/metabolism/ultrastructure Mating Factor Microscopy, Immunoelectron/*methods Mutation Peptides/metabolis;"
Notes:		"MedlineMulholland, J Konopka, J Singer-Kruger, B Zerial, M Botstein, D eng R01 GM046406/GM/NIGMS NIH HHS/ R37 GM046406/GM/NIGMS NIH HHS/ GM-46406/GM/NIGMS NIH HHS/ Research Support, U.S. Gov't, P.H.S. 1999/03/09 Mol Biol Cell. 1999 Mar; 10(3):799-817. doi: 10.1091/mbc.10.3.799"