title: Isolation of an inhibitory protein for the cyclic guanosine 3','5'-monophosphate phosphodiesterase of bovine rod outer segments.
abstract: Cyclic guanosine 3',5'-monophosphate phosphodiesterase in crude extracts from bovine rod outer segments can be activated by the addition of bleached rod outer segment membranes and GTP. In the absence of rhodopsin-containing membranes, the phosphodiesterase specific activity decreases with increasing concentration. A trypsin-sensitive inhibitor believed to be responsible for this phenomenon can be separated from the phosphodiesterase by DEAE-cellulose chromatography of the crude extract. Phosphodiesterase eluted from the DEAE-cellulose column shows considerably less concentration-dependence than in the crude extract. This partially purified phosphodiesterase was used as the substrate to assay for inhibitor. A GTPase which is active only in the presence of bleached rod outer segment membranes coelutes with the phosphodiesterase and is distinct from the phosphodiesterase inhibitor we have isolated.
mesh_terms: D015106:3',5'-Cyclic-GMP Phosphodiesterases / Q000037:antagonists & inhibitors*; D000818:Animals; D002417:Cattle; D004355:Drug Stability; D004789:Enzyme Activation; D020558:GTP Phosphohydrolases / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000494:pharmacology; D006358:Hot Temperature; D008566:Membranes / Q000032:analysis; D010786:Photoreceptor Cells / Q000032:analysis / Q000201:enzymology*; D011506:Proteins / Q000302:isolation & purification* / Q000494:pharmacology; D014357:Trypsin / Q000494:pharmacology
chemical_list: D011506:Proteins; D006160:Guanosine Triphosphate; D015106:3',5'-Cyclic-GMP Phosphodiesterases; D014357:Trypsin; D020558:GTP Phosphohydrolases