Related Experiment Video
Updated: May 9, 2026

Assay for Adhesion and Agar Invasion in S. cerevisiae
Published on: November 8, 2006
The STE4 and STE18 genes of yeast encode potential beta and gamma subunits of the mating factor receptor-coupled G
M Whiteway1, L Hougan, D Dignard
1Genetic Engineering Section NRC Biotechnology Research Institute, Montreal, Quebec, Canada.
Abstract:
The STE4 and STE18 genes are required for haploid yeast cell mating. Sequencing of the cloned genes revealed that the STE4 polypeptide shows extensive homology to the beta subunits of mammalian G proteins, while the STE18 polypeptide shows weak similarity to the gamma subunit of transducin. Null mutations in either gene can suppress the haploid-specific cell-cycle arrest caused by mutations in the SCG1 gene (previously shown to encode a protein with similarity to the alpha subunit of G proteins). We propose that the products of the STE4 and STE18 genes comprise the beta and gamma subunits of a G protein complex coupled to the mating pheromone receptors. The genetic data suggest pheromone-receptor binding leads to the dissociation of the alpha subunit from beta gamma (as shown for mammalian G proteins), and the free beta gamma element initiates the pheromone response.
Related Concept Videos
Yeast Signaling
G-protein Coupled Receptors
Protein Complexes with Interchangeable Parts
The SCF ubiquitin ligase is a protein complex of five individual proteins. This complex attaches ubiquitin to other target proteins to mark them for degradation. In order to...
G-protein Coupled Receptors
Activation and Inactivation of G Proteins
Gene Regulation During Sporulation

