The human calbindin D28k (CALB1) and calretinin (CALB2) genes are located at 8q21.3→q22.1 and 16q22→q23, respectively, suggesting a common duplication with the carbonic anhydrase isozyme loci
The genes encoding calbindin D28k (CALB1) and calretinin (CALB2), two closely related calcium-binding proteins, were mapped by in situ hybridization to the 8q21.3→ q22.1 and 16q22→q23 regions of the human genome, respectively. These localizations match the chromosomal regions where the carbonic anhydrase isozyme gene cluster (CA1 CA2, CA3) and the related gene CA7 have been described, respectively. This suggests a common duplication·the calbindin/calretinin and the carbonic anhydrase ancestral genes.