Mediation of the attachment or fusion step in vesicular transport by the GTP-binding Ypt1 protein.
The function of the guanosine triphosphate (GTP)-binding protein Ypt1 in regulating vesicular traffic was studied in a cell-free system that reconstitutes transport from the endoplasmic reticulum to the Golgi. Blocking the Ypt1 protein activity resulted in accumulation of vesicles that act as an intermediate passing between the two compartments. The Ypt1 protein was found on the outer side of these vesicles. The transport process is completed by fusion of these vesicles with the acceptor compartment, and Ypt1 protein activity was needed for this step. Thus, a specific GTP-binding protein is required for either attachment or fusion (or both) of secretory vesicles with the acceptor compartment during protein secretion.
Segev
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Department of Pharmacological and Physiological Sciences, University of Chicago, IL 60637.
D002474:Cell-Free System; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005656:Fungal Proteins / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006031:Glycosylation; D006056:Golgi Apparatus / Q000378:metabolism; D007700:Kinetics; D000072235:Mating Factor; D008861:Microsomes / Q000378:metabolism; D010455:Peptides / Q000235:genetics; D011498:Protein Precursors / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D011506:Proteins / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D014357:Trypsin / Q000494:pharmacology; D020691:rab GTP-Binding Proteins
D005656:Fungal Proteins; D010455:Peptides; D011498:Protein Precursors; D011506:Proteins; D029701:Saccharomyces cerevisiae Proteins; D000072235:Mating Factor; D014357:Trypsin; D019204:GTP-Binding Proteins; C060755:YPT1 protein, S cerevisiae; D020691:rab GTP-Binding Proteins