Primary structure and immunohistochemical localization of dog osteocalcin.

We determined the complete amino-acid sequence of dog osteocalcin and cultured the antibody against it. We also examined the immunohistochemical localization of osteocalcin on dog bones.Dog osteocalcin consisted of 49 amino acid residues (MW: 5, 682), and the complete sequence was determined to be YLDSGLGAPVPYPDPLXPKRXVCXLNPNCDELADHIGFQEAYRRFYGPV (X=Gla). Although Serine-4 is unique to dog osteocalcin, a high homology was seen between the osteocalcin from dogs and that from other mammals.Osteocalcin immunoreactivity was detected in osteoblasts, osteocytes and some preosteoblasts. In osteoclasts, both positively and negatively stained cells were observed. However, fibroblasts and chondrocytes were not stained positively.These results should prove useful in various bone metabolic studies using dogs as an experimental animal.