Specific immunological detection of the (V+C)(-) fibronectin isoform.

The population of fibronectins in adult mammalian cartilage includes high levels of a cartilage-specific (V+C)(-) isoform which lacks the V, III-15, and I-10 segments and thus contains a novel junction between protein segments III-14 and I-11. We report production of a monoclonal antibody specific for (V+C)(-) fibronectin without cross-recognition of V(+)C(+) and V(-)C(+) isoforms found in plasma and other tissues. Presentation of epitope to this antibody requires the III-14/I-11 junction, but the epitope itself extends beyond 14 amino acids immediately surrounding the junction site and involves a conformational change in III-14 and/or the N-terminal portion of I-11.