RETINAL CYCLIC-GMP PHOSPHODIESTERASE GAMMA-SUBUNIT - IDENTIFICATION OF FUNCTIONAL RESIDUES IN THE INHIBITORY REGION

Previously, we have domain-mapped the 87 amino acid PDEγ inhibitory subunit of the retinal phosphodiesterase (PDE) αβγ2 complex using synthetic peptides [18]. The PDEγ subunit has a binding domain for transducin-α (Tα) and for PDEα β within residues # 24-45 and an inhibitory region for PDEα β within residues # 80-87. In order to establish the role of individual amino acids in the function of the PDEγ inhibitory subunit, peptides of PDEγ # 63-87 and mutant peptides were synthesized and utilized in PDE inhibition assays. The following peptides exhibited a decreased ability to inhibit PDEα β: All were from PDEγ # 63-87; PDEγ Tyr 84 → Gly, PDEγ Phe 73 → Gly and PDEγ Gln 83 → Gly. © 1991.