CLONING AND EXPRESSION IN ESCHERICHIA-COLI OF A CDNA-ENCODING A DEVELOPMENTALLY-REGULATED CA2+-BINDING PROTEIN FROM DICTYOSTELIUM-DISCOIDEUM

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 moths of many Ca2+-binding proteins. When expressed in bacteria as a GST fusion protein, CBP1 binds Ca2+ in a Ca-45(2+) 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.