GONUTS has been updated to MW1.31 Most things seem to be working but be sure to report problems.

Have any questions? Please email us at ecoliwiki@gmail.com

PMID:2161538

From GONUTS
Jump to: navigation, search
Citation

Blumer, KJ and Thorner, J (1990) Beta and gamma subunits of a yeast guanine nucleotide-binding protein are not essential for membrane association of the alpha subunit but are required for receptor coupling. Proc. Natl. Acad. Sci. U.S.A. 87:4363-7

Abstract

Conditions were devised to demonstrate GTP-regulated coupling between the yeast STE2-encoded receptor and its cognate guanine nucleotide-binding protein (G protein). Treatment of partially purified membranes with guanosine 5'-[gamma-thio]triphosphate (GTP[gamma-S]) converted the receptor from a high-affinity state (Kd = 17 nM) to a much lower affinity state (Kd approximately 150 nM), as judged by three independent criteria: rate of ligand (alpha-factor) dissociation, equilibrium binding, and antagonist competition. Expression of STE2 from the GAL1 promoter in MATa/MAT alpha diploids, which do not express GPA1 (encoding G protein alpha subunit, G alpha), STE4 (encoding G protein beta subunit, G beta), and STE18 (encoding G protein gamma subunit, G gamma) but do express another G protein alpha subunit (product of GPA2), yielded a single class of low-affinity receptors that were GTP[gamma-S]-insensitive, indicating that STE2 gene product cannot couple productively with other G proteins, even in the absence of competition by its cognate G protein. By using gpa1, STE4, and ste18 mutations, it was found that all three G protein subunits were required for functional coupling, as judged by the absence of high-affinity receptors when any of the three gene products was altered. This finding demonstrates that G beta and G gamma subunits are essential for formation of a productive complex between a G alpha subunit and its corresponding receptor. Wild-type STE4 and STE18 gene products were not essential for membrane localization of the GPA1 gene product, as indicated by cell fractionation and immunological analyses, suggesting that G beta and G gamma subunits interact with the receptor or make the G alpha subunit competent to associate correctly with the receptor, or both.

Links

PubMed PMC54110

Keywords

Cell Membrane/metabolism; GTP-Binding Proteins/physiology; GTP-Binding Proteins/ultrastructure; Genes, Fungal; Macromolecular Substances; Peptides/metabolism; Protein Binding; Receptors, Cell Surface/physiology; Receptors, Mating Factor; Receptors, Peptide; Saccharomyces cerevisiae; Signal Transduction; Structure-Activity Relationship; Transcription Factors

Significance

Annotations

Gene product Qualifier GO ID GO term name Evidence Code with/from Aspect Notes Status


See also

References

See Help:References for how to manage references in GONUTS.