Separate roles for N- and C-termini of the STE4 (β) subunit of the Saccharomyces cerevisiae G protein in the mediation of the growth arrest. Lack of growth-arresting activity of mammalian βγ complexes

Coria, Roberto; Ongay‐Larios, Laura; Birnbaumer, Lutz

doi:10.1002/(sici)1097-0061(199601)12:1<41::aid-yea883>3.0.co;2-1

Cited by 6 publications

(1 citation statement)

References 35 publications

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“…The actual model for the receptor‐Gαβγ complex specifies interactions between the receptor's third cytoplasmic loop, the Gα N‐ and C‐termini, and the Gβ subunit, in addition to a contact between the receptor's C‐terminal tail and the Gβγ dimer [33]. The regions of the yeast Gβ that interact with downstream signaling components have been identified genetically and map to the N‐terminal coiled coil of Gβγ [34,35]. None of the residues on yeast Gβγ that are assumed to form part of the effector site lie within a Gα/Gβγ interface.…”

Section: Discussionmentioning

confidence: 99%

The Leu‐132 of the Ste4(Gβ) subunit is essential for proper coupling of the G protein with the Ste2 α factor receptor during the mating pheromone response in yeast

et al. 2000

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In order to identify amino acid residues of Ste4p involved in receptor recognition and/or receptor-G protein coupling, we employed random in vitro mutagenesis and a genetic screening to isolate mutant Ste4p subunits with altered pheromone response. We generated a plasmid library containing randomly mutagenized Ste4 ORFs, followed by phenotypic selection of ste4p mutants by altered K K pheromone response in yeast cells. Subsequently, we analyzed mutant ste4-10 which has a replacement of the almost universally conserved leucine 132 by phenylalanine. This residue lies in the first blade of the L L propeller structure proposed by crystallographic analysis. By overexpression experiments we found that mutant ste4p subunit triggers the mating pathway at wild type levels in both wild type and receptorless strains. When expressed in a ste4 background, however, the mutant G protein is activated inefficiently by mating pheromone in both a and K K cells. The mutant ste4-10p was tested in the two-hybrid system and found to be defective in its interaction with the Gpa1p, but has a normal association with the C-termini end of the Ste2p receptor. These observations strongly suggest that the Leu-132 of the Ste4p subunit is essential for efficient activation of the G protein by the pheromonestimulated receptor and that this domain could be an important point for physical interaction between the GL L and the GK K subunits.z 2000 Federation of European Biochemical Societies.

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Section: Discussionmentioning

confidence: 99%

The Leu‐132 of the Ste4(Gβ) subunit is essential for proper coupling of the G protein with the Ste2 α factor receptor during the mating pheromone response in yeast

et al. 2000

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The Gβ(KlSte4p) subunit of the heterotrimeric G protein has a positive and essential role in the induction of mating in the yeast Kluyveromyces lactis

Kawasaki

Saviñón‐Tejeda

Ongay‐Larios

et al. 2005

Yeast

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In the yeast Saccharomyces cerevisiae the Gβγ dimer of the heterotrimeric G protein transduces a pheromone signal from serpentine receptor to a MAP kinase cascade that activates the mating response pathway. Haploid cells lacking the Gβ subunit do not respond to sexual pheromone, leading to sterility. In this work we demonstrate that the β-subunit of Kluyveromyces lactis, encoded by the KlSTE4 gene, is a component of the G protein, and that its disruption gives rise to sterile cells. However, unlike Ste4p in S. cerevisiae, its overexpression does not induce growth arrest or promote mating. It has been shown that in K. lactis, the Gα subunit has a positive role in the mating process, hence the resulting double Gα Gβ mutant was viable and sterile. Here we show that the overproduction of Gβ subunit fails to rescue Gα mutant from sterility and that expression of a constitutive active allele of Gα enhances transcription of the KlSTE4 gene. The mating pathway triggered by the Gβ-subunit requires a functional KlSte12p transcription factor. Gβ has a 10-fold higher association rate with the Gα1 subunit involved in pheromone response than with Gα2, the protein involved in cAMP regulation in K. lactis. Additionally, the Gβ-subunit from K. lactis is able to interact with the Gα-subunit from S. cerevisiae but fails to restore the mating deficiency of Scste4 mutant. The data presented indicate that the mating pathway of K. lactis is positively and cooperatively regulated by both the Gα and the Gβ subunits.

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Enhancement of pheromone response by RGS9 and Gβ5 in yeast

Ajit

Young

2004

Biochemical and Biophysical Research Communications

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Separate roles for N- and C-termini of the STE4 (β) subunit of the Saccharomyces cerevisiae G protein in the mediation of the growth arrest. Lack of growth-arresting activity of mammalian βγ complexes

Cited by 6 publications

References 35 publications

The Leu‐132 of the Ste4(Gβ) subunit is essential for proper coupling of the G protein with the Ste2 α factor receptor during the mating pheromone response in yeast

The Leu‐132 of the Ste4(Gβ) subunit is essential for proper coupling of the G protein with the Ste2 α factor receptor during the mating pheromone response in yeast

The Gβ(KlSte4p) subunit of the heterotrimeric G protein has a positive and essential role in the induction of mating in the yeast Kluyveromyces lactis

Enhancement of pheromone response by RGS9 and Gβ5 in yeast

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