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Biomedical subjects

J Strathern

Publications and source records attributed to J Strathern.

3 recordsLinked to original sources
PubMed1989

Coconversion of flanking sequences with homothallic switching.

Homothallic switching in S. cerevisiae involves replacing the DNA of the expressed allele at the mating type locus (MAT) with a duplicate of sequences from the unexpressed loci HML or HMR. The MATa and MAT alpha alleles differ by a DNA substitution that is flanked by sequences in common to MAT, and the donor loci HML and HMR. Using restriction site polymorphisms between MAT and the donor loci, we demonstrate that the extent of MAT DNA that is replaced during switching is variable and that there is a gradient of coconversion across the X region. Coconversion events occur on both sides of the double-strand cleavage by the HO gene product. The two cells produced after a switch often differ at the flanking site, indicating a DNA heteroduplex intermediate.

Alleles↗
PubMed1988

a/Alpha-specific repression by MAT alpha 2.

The product of the MAT alpha 2 gene is a DNA-binding protein that acts as a repressor of two different sets of cell type-specific genes. In alpha cells, the alpha 2 protein represses the transcription of several a-specific genes. In a/alpha cells, the alpha 2 protein acts together with the product of the MATa1 gene, the a1 protein, to repress several genes used by haploids in the mating process. In addition to the mat alpha 2 mutations that result in defects in both types of regulation, other mat alpha 2 alleles have been described that result in defects in the repression of a-specific genes but that do not affect the ability of the alpha 2 and a1 proteins to interact to repress the haploid-specific genes. We report here the isolation of a new class of mat alpha 2 mutations that do not affect the ability of the alpha 2 protein to repress a-specific genes, but that interfere with the ability of the alpha 2 protein to interact with the a1 protein to repress the haploid-specific genes and establish the a/alpha cell type. These mutations may help determine the means by which the a1 protein interacts with alpha 2 to expand the set of genes under its control.

Amino Acid Sequence↗