Figure 5. Schematic domain structure of members of the calbindin subfamily in rat (R. norvegicus), fly (D. melanogaster), and sea urchin (S. purpuratus).

Domains 1, 3, 4, and 5 are present in all the proteins. The second domain doesn't bind calcium in the calbindin 1 protein, while it does in calbindin 2, and in Drosophila and S. purpuratus' calbindin-D32k. Domain 6 is present in Drosophila calbindin-D32k and S. purpuratus calbindin-D32k, but it is only able to bind calcium in the latter. Pairwise similarities of domains between proteins were calculated by aligning the domains as predicted by ScanProsite.