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STE2 encodes a component of the S. cerevisiae alpha-pheromone receptor that is essential for induction of physiological changes associated with mating. Analysis of C-terminal truncation mutants of STE2 demonstrated that the essential sequences for ligand binding and signal transduction are included within a region containing seven putative transmembrane(More)
When Saccharomyces cerevisiae a cells bind alpha-factor pheromone, the ligand is internalized and its binding sites are lost from the cell surface in a time-, energy-, and temperature-dependent manner. This report presents direct evidence for alpha-factor-induced internalization of cell surface receptors. First, membrane fractionation on Renografin density(More)
The STE5 gene encodes an essential element of the pheromone response pathway which is known to act either after the G subunit encoded by the STE4 gene or at the same step. Mutations in STE5, designated STE5Hyp, that partially activate the pathway in the absence of pheromone were isolated. One allele (STE5Hyp-2) was shown to cause a single amino acid(More)
The pheromone response in the yeast Saccharomyces cerevisiae is mediated by a heterotrimeric G protein. The Gbetagamma subunit (a complex of Ste4p and Ste18p) is associated with both internal and plasma membranes, and a portion is not stably associated with either membrane fraction. Like Ras, Ste18p contains a farnesyl-directing CaaX box motif (C-terminal(More)
alpha-Factor receptors from Saccharomyces cerevisiae are G-protein-coupled receptors containing seven transmembrane segments. Receptors solubilized with the detergent n-dodecyl beta-D-maltoside were found to sediment as a single 8S species in glycerol density gradients. When the membranes from cells coexpressing two differentially tagged receptors were(More)
The division cycle of yeast a cells is inhibited by alpha-factor. Haploid a cells were found to bind 35S-labeled alpha-factor, whereas haploid alpha cells and diploid a/alpha cells showed little binding. The association of alpha-factor with a cells was reversible upon dilution. Unlabeled alpha-factor competed for binding of 35S-alpha-factor; the(More)
Binding of the alpha-factor pheromone to its G-protein-coupled receptor (encoded by STE2) activates the mating pathway in MATa yeast cells. To investigate whether specific interactions between the receptor and the G protein occur prior to ligand binding, we analyzed dominant-negative mutant receptors that compete with wild-type receptors for G proteins, and(More)
alpha-Factor pheromone inhibits division of yeast a cells. After prolonged exposure to alpha-factor, the cells adapt to the stimulus and resume cell division. The sst2 mutation is known to inhibit adaptation. This report examines adaptation in scg1 (also designated gpa1) and STE4Hpl (Hpl indicates haploid lethal) mutants that exhibit constitutive activation(More)
The alpha factor pheromone inhibits the division of yeast a cells. A general method was developed for isolating mutants that exhibit constitutive activation of the pheromone response pathway. A dominant allele of the STE4 locus was recovered in addition to recessive mutations in the SCG1 gene. SCG1 and STE4 are known to encode G alpha and G beta homologs,(More)
Mutations in six genes that eliminate responsiveness of Saccharomyces cerevisiae a cells to alpha-factor were examined by assaying the binding of radioactively labeled alpha-factor to determine whether their lack of responsiveness was due to the absence of alpha-factor receptors. The ste2 mutants, known to be defective in the structural gene for the(More)