Characterization of transducin from bovine retinal rod outer segments: use of monoclonal antibodies to probe the structure and function of the α subunit

A panel of monoclonal antibodies has been developed against the T sub( alpha ), T sub( beta ) and T sub( gamma ) subunits of bovine transducin. Two anti-T sub( alpha ) antibodies from this panel (TF15 and TF16) and a third one (4A) against frog T sub( alpha ) were characterized. Each of these monoclonal antibodies recognizes a different region of T sub( alpha ) and has a specific effect on the function of transducin. The results suggest that the inhibitory effects of 4A are due to a simultaneous steric blockage of both the interaction of T sub( alpha ) with T sub( beta gamma ) and their binding to photolyzed rhodopsin.