Overexpression of the CDC25 gene, an upstream element of the RAS/adenylyl cyclase pathway in Saccharomyces cerevisiae, allows immunological identification and characterization of its gene product.

The product of the START gene CDC25, an upstream element of the RAS/adenylyl cyclase pathway in Saccharomyces cerevisiae, was identified using specific antibodies raised against a chimeric beta-galactosidase/CDC25 protein. The CDC25 protein is poorly expressed and can be detected only when the CDC25 gene is overexpressed under the control of the galactose-inducible GAL1-10 strong promoter elements. It has a molecular weight of 180,000, is not glycosylated and is strongly associated with the particulate fraction. After deletion of residues 1255-1550 the protein is found in the soluble fraction.