Ste5 RING-H2 domain: role in Ste4-promoted oligomerization for yeast pheromone signaling.

Ste5 is a scaffold for the mitogen-activated protein kinase (MAPK) cascade components in a yeast pheromone response pathway. Ste5 also associates with Ste4, the beta subunit of a heterotrimeric guanine nucleotide-binding protein, potentially linking receptor activation to stimulation of the MAPK cascade. A RING-H2 motif at the Ste5 amino terminus ...
is apparently essential for function because Ste5(C177S) and Ste5(C177A C180A) mutants did not rescue the mating defect of a ste5Delta cell. In vitro Ste5(C177A C180A) bound each component of the MAPK cascade, but not Ste4. Unlike wild-type Ste5, the mutant did not appear to oligomerize; however, when fused to a heterologous dimerization domain (glutathione S-transferase), the chimeric protein restored mating in an ste5Delta cell and an ste4Delta ste5Delta double mutant. Thus, the RING-H2 domain mediates Ste4-Ste5 interaction, which is a prerequisite for Ste5-Ste5 self-association and signaling.
Mesh Terms:
Adaptor Proteins, Signal Transducing, Amino Acid Sequence, Binding Sites, Calcium-Calmodulin-Dependent Protein Kinases, Carrier Proteins, Dimerization, Fungal Proteins, GTP-Binding Protein beta Subunits, GTP-Binding Proteins, Genetic Complementation Test, Glutathione Transferase, Heterotrimeric GTP-Binding Proteins, Molecular Sequence Data, Peptides, Pheromones, Point Mutation, Polymers, Recombinant Fusion Proteins, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Signal Transduction, Transformation, Genetic
Science
Date: Oct. 03, 1997
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