Substitutions in the Pheromone-Responsive G_ß Protein of Saccharomyces cerevisiae Confer a Defect in Recovery from Pheromone Treatment

Corresponding author: David E. Stone, Laboratory for Molecular Biology (M/C 567), Department of Biological Sciences, University of Illinois at Chicago, 900 South Ashland Avenue, Chicago, IL 60607, U62248{at}uicvm.uic.edu (E-mail).

Communicating editor: M. D. ROSE

The pheromone-responsive G protein of Saccharomyces cerevisiae, Gpa1p, stimulates an adaptive mechanism that downregulates the mating signal. In a genetic screen designed to identify signaling elements required for Gpa1p-mediated adaptation, a large collection of adaptive-defective (Adp^-) mutants were recovered. Of the 49 mutants characterized thus far, approximately three-quarters exhibit a dominant defect in the negative regulation of the pheromone response. Eight of the dominant Adp^- mutations showed tight linkage to the gene encoding the pheromone-responsive G_ß, STE4. Sequence analysis of the STE4 locus in the relevant mutant strains revealed seven novel STE4 alleles, each of which was shown to disrupt proper regulation of the pheromone response. Although the STE4 mutations had only minor effects on basal mating pathway activity, the mutant forms of G_ß dramatically affected the ability of the cell to turn off the mating response after exposure to pheromone. Moreover, the signaling activity of the aberrant G_ß subunits was suppressed by G322E, a mutant form of Gpa1p that blocks the pheromone response by sequestering G_ß, but not by E364K, a hyperadaptive form of Gpa1p. On the basis of these observations, we propose that Gpa1p-mediated adaptation involves the binding of an unknown negative regulator to G_ß.

This article has been cited by other articles:

				E. E. Bar, A. T. Ellicott, and D. E. Stone G{beta}{gamma} Recruits Rho1 to the Site of Polarized Growth during Mating in Budding Yeast J. Biol. Chem., June 6, 2003; 278(24): 21798 - 21804. [Abstract] [Full Text] [PDF]

				E. Blackwell, I. M. Halatek, H.-J. N. Kim, A. T. Ellicott, A. A. Obukhov, and D. E. Stone Effect of the Pheromone-Responsive G{alpha} and Phosphatase Proteins of Saccharomyces cerevisiae on the Subcellular Localization of the Fus3 Mitogen-Activated Protein Kinase Mol. Cell. Biol., February 15, 2003; 23(4): 1135 - 1150. [Abstract] [Full Text] [PDF]

				M. V. Metodiev, D. Matheos, M. D. Rose, and D. E. Stone Regulation of MAPK Function by Direct Interaction with the Mating-Specific Galpha in Yeast Science, May 24, 2002; 296(5572): 1483 - 1486. [Abstract] [Full Text] [PDF]

				J. Kim, A. Couve, and J. P. Hirsch Receptor Inhibition of Pheromone Signaling Is Mediated by the Ste4p Gbeta Subunit Mol. Cell. Biol., January 1, 1999; 19(1): 441 - 449. [Abstract] [Full Text] [PDF]