Immunohistochemical localization of calbindins (28K and 9K) in the tissues of the baboon Papio ursinus.

An indirect immunoperoxidase procedure was used to detect the presence of calbindin-D28K and calbindin-D9K in the cerebellum, kidney, and duodenum of the baboon Papio ursinus. Antibodies to chick calbinding-D28K and to both rat and mouse calbindin-D9K were used. The cerebellum and kidney were shown to contain calbindin-D28K; the doudenum contained calbindin-D9K. In the cerebellum, positive staining was found in the Purkinje cells only; in the kidney, positive staining was found in the distal convoluted tubules, connecting tubules, and collecting tubules, extending deep into the medullary regions of the kidney. Staining in the duodenum was confined to the enterocytes of the villi, with no stain present in the crypt regions or goblet cells. Thus the baboon, a primate, contains the larger of the calbindins in both the cerebellum and kidney as does the human and monkey, but its distribution in the kidney is more generalized than that found in humans. The molecular weight of calbindin-D9K was found to be similar to that found in other animals. However, the calbindin-D28K from the baboon tissues appears to be slightly smaller than the protein found in other animals and may therefore be of similar size to the human calbindin-D28K (Mr 26,000).