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Mol Biol Cell

Title:		Evidence that mating by the Saccharomyces cerevisiae gpa1Val50 mutant occurs through the default mating pathway and a suggestion of a role for ubiquitin-mediated proteolysis
Author(s):		Xu BE; Kurjan J;
Address:		"Department of Microbiology and Molecular Genetics, University of Vermont, College of Medicine, Burlington, USA"
Journal Title:		Mol Biol Cell
Year:		1997
Volume:		8
Issue:		9
Page Number:		1649 - 1664
DOI:		10.1091/mbc.8.9.1649
ISSN/ISBN:		1059-1524 (Print) 1059-1524 (Linking)
Abstract:		"The yeast G alpha subunit, Gpa1p, plays a negative role in the pheromone response pathway. The gpa1Val50 mutant was previously shown to have a growth defect, consistent with the GTPase defect predicted for this mutation, and greatly reduced mating. Various explanations for the mating defect have been proposed. One approach to analyze the gpa1Val50 mating defect involved epistasis analysis. The low mating of the gpa1Val50 mutant was independent of the pheromone receptor; therefore, it results from intracellular activation of the pathway, consistent with a GTPase defect. This result suggests that gpa1Val50 mating occurs through the default rather than the chemotropic pathway involved in pheromone response. We therefore tested the effect of a spa2 mutation on gpa1Val50 mating, because Spa2p has been implicated in the default pathway. The spa2 mutation greatly reduced the mating of the gpa1Val50 mutant, suggesting that gpa1Val50 mating occurs predominantly through the default pathway. In a second approach to investigate the gpa1Val50 phenotypes, suppressors of the gpa1Val50 mating defect were isolated. Two suppressor genes corresponded to SON1/UFD5 and SEN3, which are implicated in ubiquitin-mediated proteolysis. On the basis of these results, we suggest that a positive component of the default mating pathway is subject to ubiquitin-mediated degradation"
Keywords:		"Cloning, Molecular Fungal Proteins/genetics/physiology *GTP-Binding Protein alpha Subunits GTP-Binding Protein alpha Subunits, Gq-G11 *GTP-Binding Protein beta Subunits GTP-Binding Proteins/*genetics/metabolism/*physiology Gene Expression Regulation, Fung;"
Notes:		"MedlineXu, B E Kurjan, J eng GM40585/GM/NIGMS NIH HHS/ Research Support, U.S. Gov't, P.H.S. 1997/10/06 Mol Biol Cell. 1997 Sep; 8(9):1649-64. doi: 10.1091/mbc.8.9.1649"