Effects of expression of mammalian G alpha and hybrid mammalian-yeast G alpha proteins on the yeast pheromone response signal transduction pathway.

摘要: Scg1, the product of Saccharomyces cerevisiae SCG1 (also called GPA1) gene, is homologous to alpha subunits G proteins involved in signal transduction mammalian cells. Scg1 negatively controls pheromone response pathway haploid Either pheromonal activation or an scg1 null mutation relieves negative control and leads arrest cell growth G1 phase cycle. Expression rat s was previously shown complement defect mutants while not allowing mating. We have extended this analysis examine effects short form (which lacks 15 amino acids present long form), i2, o, Scg1-mammalian hybrids. In addition, we found that constructs able are also inhibit mating when expressed a wild-type strain. Overexpression has similar inhibitory effect. These results consistent with model proposed for action as component heterotrimeric protein which beta gamma (Ste4/Ste18) activates after dissociation from Scg1. They suggest can interact prevent but unable receptors activate pathway.