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Genetics

Title:		Control of adaptation to mating pheromone by G protein beta subunits of Saccharomyces cerevisiae
Author(s):		Grishin AV; Weiner JL; Blumer KJ;
Address:		"Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri 63110"
Journal Title:		Genetics
Year:		1994
Volume:		138
Issue:		4
Page Number:		1081 - 1092
DOI:		10.1093/genetics/138.4.1081
ISSN/ISBN:		0016-6731 (Print) 0016-6731 (Linking)
Abstract:		"The STE4 gene of the yeast Saccharomyces cerevisiae encodes the beta subunit of a heterotrimeric G protein that mediates response to mating pheromones and influences recovery from pheromone-induced growth arrest. To explore how G beta subunits regulate response and recovery (adaptation), we isolated and characterized signaling-defective STE4 alleles (STE4sd). STE4sd mutations resulted in amino acid substitutions in the N-terminal region of Ste4p, proximal to the first of seven repeat units conserved in G protein beta subunits. Genetic tests indicated that STE4sd mutations disrupted functions of Ste4p required for inducing pheromone responses. Wild-type cells that overexpressed STE4sd alleles displayed apparently normal initial responses to pheromone as judged by quantitative mating, G1 arrest and transcriptional assays. However, after undergoing initial G1 arrest, wild-type cells overexpressing STE4sd alleles recovered more quickly from division arrest, suggestive of a hyperadaptive phenotype. Because hyperadaptation occurred when STE4sd alleles were overexpressed in cells lacking Sst1p (Bar1p), Sst2p or the C-terminal domain of the alpha-factor receptor, this phenotype did not involve three principal modes of adaptation in yeast. However, hyperadaptation was abolished when STE4sd mutations were combined in cis with a deletion that removes a segment of Ste4p (residues 310-346) previously implicated in adaptation to pheromone. These results indicate that G beta subunits possess two independent activities, one required for triggering pheromone response and another that promotes adaptation. Potential models for G beta subunit-mediated adaptation are discussed"
Keywords:		"Adaptation, Physiological Amino Acid Sequence Base Sequence Fungal Proteins/genetics/*physiology *GTP-Binding Protein beta Subunits GTP-Binding Proteins/*physiology *Heterotrimeric GTP-Binding Proteins Mating Factor Molecular Sequence Data Peptides/geneti;"
Notes:		"MedlineGrishin, A V Weiner, J L Blumer, K J eng GM-44592/GM/NIGMS NIH HHS/ Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, P.H.S. 1994/12/01 Genetics. 1994 Dec; 138(4):1081-92. doi: 10.1093/genetics/138.4.1081"