title: Immunologic characterization of the photoreceptor outer segment cyclic GMP phosphodiesterase.
abstract: High affinity (KD approximately 1 X 10(-9) M) monoclonal antibodies (ROS-1 and ROS-2) were prepared to bovine photoreceptor outer segment cGMP phosphodiesterase. ROS-1 immunoadsorbed greater than 95% of the cGMP phosphodiesterase activity from a detergent-solubilized bovine retina extract while ROS-2 immunoadsorbed only a subfraction of the same activity. Sodium dodecyl sulfate gel analysis of these immunoadsorbates demonstrated that ROS-1 and ROS-2 specifically adsorbed only peptides that comigrated with purified rod outer segment phosphodiesterase. Limited trypsin digestion of purified rod outer segment phosphodiesterase greatly reduced its affinity for ROS-1 but not ROS-2. When a crude heat-stable inhibitor fraction was added back to the activated enzyme, the affinity for ROS-1 was restored, suggesting that the inhibitor was necessary for ROS-1 binding. ROS-1 but not ROS-2 was found to inhibit cGMP phosphodiesterase which had been activated either by dilution or guanyl nucleotide. The inhibitory property of ROS-1 may provide a useful probe for directly studying the effects of this phosphodiesterase on the phototransduction response in the retina. Sodium dodecyl sulfate gel analysis demonstrated that the ROS-1 immunoadsorbates from mammals, fish, and amphibia contained peptides of similar mobility. Immunocytochemistry performed with ROS-1 and fluorescein isothiocyanate-conjugated rabbit anti-mouse IgG localized the antigenic determinant to both rod and cone outer segments suggesting the presence of an antigenically similar phosphodiesterase in both types of photoreceptors.
mesh_terms: D015106:3',5'-Cyclic-GMP Phosphodiesterases / Q000378:metabolism*; D000818:Animals; D000911:Antibodies, Monoclonal / Q000302:isolation & purification; D000936:Antigen-Antibody Complex; D002417:Cattle; D005455:Fluorescent Antibody Technique; D007074:Immunoglobulin G / Q000302:isolation & purification; D007700:Kinetics; D010786:Photoreceptor Cells / Q000201:enzymology*; D012374:Rod Cell Outer Segment / Q000201:enzymology*
chemical_list: D000911:Antibodies, Monoclonal; D000936:Antigen-Antibody Complex; D007074:Immunoglobulin G; D015106:3',5'-Cyclic-GMP Phosphodiesterases