Cloning and characterization of Xenopus dicalcin, a novel S100-like calcium-binding protein in Xenopus eggs

To contribute to the study of the calcium-signaling mechanism of egg, we cloned and characterized a 26 kDa Ca(2+)-binding protein from Xenopus laevis eggs, a homologue of Rana catesbeiana dicalcin (renamed from p26olf) that was isolated from the olfactory epithelium. The primary structure of Xenopus dicalcin shows approximately 61% identity to that of Rana dicalcin and consists of two S100-like regions aligned in tandem, as seen in Rana dicalcin. Genomic Southern blot analysis indicated that Xenopus dicalcin is a unique orthologue of Rana dicalcin. Northern blot analysis showed that Xenopus dicalcin mRNA is expressed in Xenopus eggs and also in other tissues. These results indicated that Xenopus dicalcin is a novel S100-like Ca(2+)-binding protein in Xenopus eggs.