The Mat alpha 2 homeodomain protein plays a pivotal role in the control of cell type in Saccharomyces cerevisiae. The homeodomain in the C-terminal region of Mat alpha 2 functions as a DNA-binding domain and the N-terminal region, containing two cysteine residues at positions 33 and 34, is thought to be involved in formation of Mat alpha 2 homodimers via disulfide bonds. mat alpha 2 mutants, isolated in a previous study, in which haploid-specific genes cannot be repressed by the Matal-Mat alpha 2 heterodimer but a-specific genes can be repressed by the Mat alpha 2 homodimer, were found to produce mutant Mat alpha 2 with a substitution of tyrosine or phenylalanine for Cys33. To clarify the role of Cys33 and Cys34 in the Mat alpha 2 protein, we generated several mat alpha 2 mutants by site-directed mutagenesis which had serine residues in place of these Cys residues. Transforming MATa cells with plasmids carrying these mat alpha 2 (MAT alpha 1+) mutations rendered transformants unable to mate. Northern blot analysis revealed that transcription of the a-specific gene STE2 and the haploid-specific locus RME1 in these transformants is repressed to the same level as in wild-type MATa/MAT alpha cells. We concluded that neither Cys33 nor Cys34 is required for repression of a-specific genes by the Mat alpha 2 homodimer or of haploid-specific genes by the Matal-Mat alpha 2 heterodimer, and therefore suggest that Mat alpha 2 homodimer formation in vivo is not mediated by disulfide linkage.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Annotation Extension||Reference|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Assay||Construct||Conditions||Strain Background||Reference|