A monoclonal antibody against dentin phosphophoryn recognizes a bone protein(s) appearing at the beginning of ossification.

Decalcified and nondecalcified sections of fetal bovine tibia were stained immunohistochemically with a monoclonal antibody against dentin phosphophoryn. In the epiphyseal portion of the long bone, osteoblasts, osteocytes and the bone matrix were stained, but chondrocytes and the cartilage matrix were not. Similar staining was observed in the epiphyseal and diaphyseal portions of bones. These findings suggest that a protein(s) with the same epitope as phosphophoryn may be synthesized and secreted by osteoblasts at the beginning of ossification and may be involved in mineralization of bone tissue. On Western blots of proteins extracted from fetal bovine bone, the antibody reacted with two bands of molecular weights of about 71,000 and 63,000. These proteins and antibody(s) to the proteins may be useful for detection of the phenotype of osteogenesis.