Characterization of monoclonal antibodies to human protein 1/Clara cell 10 kilodalton protein

Human protein 1/Clara cell Mr 10 000 protein consists of two identical subunits of seventy amino acid residues each. In the present study, eight clones of monoclonal antibodies against native protein 1 were prepared and their respective epitopes were immunochemically and immunohistochemically characterized using native protein 1, truncated recombinant protein 1 and synthesized peptides. Among the clones, three designated as TY-5, TY-7 and TY-8 recognized amino acid residues 7-16, residues 19-28, and residues 39-46, respectively, all of which comprise the hydrophobic cavity of protein 1, possibly associated with chemical binding function. With the exception of TY-4, the remaining clones recognized residues 61-68 which are exposed to solvent. The epitope of TY-4 remains undetermined; Proper selection and combination of clones and recombinant protein 1 may be useful for fundamental and clinical studies of protein 1.