Active sites of the cyclic GMP phosphodiesterase γ-subunit of retinal rod outer segments

AbstractMonoclonal antibodies were prepared to the γ-subunit of the cGMP phosphodiesterase. One of them γp-1, suppresses the activation of phosphodiesterase through the α-subunit of transducin. The γ-subunit fragment 24–45 rich in Arg and Lys residues is involved in γp-1 binding and is essential for the γ-subunit interaction with transducin. Carboxypeptidase Y cleaves off seven amino acid residues from the C-terminus of the γ-subunit resulting in phosphodiesterase activation. Thus, the C-terminal fragment of γ-subunit participates in phosphodiesterase inhibition