TheSaccharomyces cerevisiae genes (CMP1 andCMP2) encoding calmodulin-binding proteins homologous to the catalytic subunit of mammalian protein phosphatase 2B

Abstract

Saccharomyces cerevisiae genomic clones that encode calmodulin-binding proteins were isolated by screening a λgt11 expression library using¹²⁵I-labeled calmodulin as probe. Among the cloned yeast genes, we found two closely related genes (CMP1 andCMP2) that encode proteins homologous to the catalytic subunit of phosphoprotein phosphatase. The presumed CMP1 protein (62999 Da) and CMP2 protein (68496 Da) contain a 23 amino acid sequence very similar to those identified as calmodulin-binding sites in many calmodulin-regulated proteins. The yeast genes encode proteins especially homologous to the catalytic subunit of mammalian phosphoprotein phosphatase type 213 (calcineurin). The products of theCMP1 andCMP2 genes were identified by immunoblot analysis of cell extracts as proteins of 62000 and 64000 Da, respectively. Gene disruption experiments demonstrated that elimination of either or both of these genes had no effect on cell viability, indicating that these genes are not essential for normal cell growth.