Monoclonal antibodies against osteonectin show conservation of epitopes across species

Several monoclonal antibodies were produced to bovine osteonectin, a major noncollagenous protein in the extracellular matrix of bone, and four were characterized. These antibodies showed different reactivities in Western immunoblots, immunoprecipitation, and indirect immunofluorescence, indicating that they recognize different epitopes on the protein. The data indicate that an epitope recognized by one of the antibodies is masked in interactions of osteonectin within cells and in the extracellular matrix. The high degree of cross-species immunoreactivity observed against bone osteonectin with these monoclonal antibodies indicates that these common epitopes have been conserved during evolution.