Yeast repressor alpha 2 binds to its operator cooperatively with yeast protein Mcm1.

To bring about repression of a family fo genes in Saccharomyces cerevisiae called the a-specific genes, two transcriptional regulatory proteins, alpha 2 and GRM (general regulator of matin type), bind cooperatively to an operator found upstream of each a-specific gene. To date, GRM has been defined only biochemically. In this communication we show that the product of a single yeast gene (MCM1) is sufficient to bind cooperatively with alpha 2 to the operator. We also show that antiserum raised against the MCM1 gene product recognizes GRM from yeast cells. These results, in combination with previous observations, provide strong evidence that MCM1 encodes the GRM activity.