Cloning and expression in Escherichia coli of a cDNA encoding a developmentally regulated Ca2+‐binding protein from Dictyostelium discoideum

Abstract

We have cloned a full-length cDNA from Dictyostelium discoideum which encodes a new Ca²⁺-binding protein. The deduced protein (termed CBP1) is composed of 156 amino acids and contains four consensus metal-ligating loop sequences found in helix-loop-helix motifs of many Ca²⁺-binding proteins. When expressed in bacteria as a GST fusion protein, CBP1 binds Ca²⁺ in a ⁴⁵Ca²⁺ overlay assay. CBP1 exhibits little amino acid sequence homology with Dictyostelium calmodulin or calfumirin-1 (CAF-1) except in the putative Ca²⁺-binding regions. Moreover, unlike calmodulin and CAF-1 expression, CBP1 mRNA is expressed preferentially during the multicellular stages of development.