Antigenic determinant and interspecies cross-reactivity of a monoclonal antibody to poly(ADP-ribose) synthetase.

A monoclonal antibody (1F4) was prepared against calf thymus poly(ADP-ribose) synthetase. It was classified as IgG1/kappa and its antigenic determinant was localized on the 46 kDa portion of the enzyme molecule which contains the site for the binding of DNA. When calf thymus DNA-binding proteins were subjected to immunostaining after electrophoresis and transblotting to a nitrocellulose filter, the native enzyme (120 kDa) and its endogenous degradation products (80, 64 and 32 kDa) were detected. When the interspecies cross-reactivity was examined using DNA-binding proteins from 6 different sources, 1F4 reacted with the 120- and 32-kDa protein bands in HeLa cells, mouse testis and chicken liver as in the case of calf thymus. These results indicate that the antigenic structures of poly(ADP-ribose) synthetase and its degradation products are highly conserved in various animal cells.