DICTYOSTELIUM-DISCOIDEUM CONTAINS A FAMILY OF CALMODULIN-RELATED EF-HAND PROTEINS THAT ARE DEVELOPMENTALLY-REGULATED

A full-length genomic DNA fragment that codes for a novel EF-hand prot ein from Dictyostelium discoideum was cloned and sequenced, The protei n is composed of 168 amino acids and contains four consensus sequences that are typical for Ca2+-binding EF-hand domains. The protein sequen ce exhibits only minor similarities to other calmodulin-type proteins from Dictyostelium. The genomic DNA harbors two short introns; their p ositions suggest that the gene is unrelated to the EF-hand proteins fr om the calmodulin group, Northern blot analysis showed that the mRNA l evel was significantly increased during development, Polyclonal antibo dies raised against the recombinant protein recognized in Western blot s a protein of about 20 kDa, Like the mRNA, also the protein was more abundant in developing cells, Overlay experiments with Ca-45(2+) indic ated that the EF-hands in fact have Ca2+-binding activity, The recent description of CBP1, another calmodulin-type Dictyostelium protein tha t is upregulated during development [Coukell et al, (1995) FEES Lett, 362, 342-346], suggests that D, discoideum contains a family of EF-han d proteins that have specific functions during distinct steps of devel opment, We therefore designate the protein described in this report as CBP2.