title: Photoreceptor GTP binding protein mediates fluoride activation of phosphodiesterase.
abstract: In this report, we show that fluoride activates dark-adapted rod outer segment phosphodiesterase, and that this activation is mediated, in analogy with adenylate cyclase, through a GTP binding protein. The GTP binding protein is released from dark-adapted rod outer segment membranes by exposure to fluoride and subsequent centrifugation. The 39-kilodalton subunit of the GTP binding protein, released from the membrane by this procedure, exhibits altered susceptibility to limited trypsin proteolysis, identical to that seen when hydrolysis-resistant GTP analogs are bound to that subunit. Repeated exposure of dark-adapted rod outer segment membranes to fluoride and subsequent centrifugation results in maximal activation of the membrane-bound phosphodiesterase. Thus, activation of phosphodiesterase by fluoride in the dark appears similar to fluoride activation of adenylate cyclase.
authors.forename: P J
authors.initials: PJ
authors.lastname: Stein
authors.forename: K R
authors.initials: KR
authors.lastname: Halliday
authors.forename: M M
authors.initials: MM
authors.lastname: Rasenick
mesh_terms: D000818:Animals; D002024:Bufo marinus; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology; D007700:Kinetics; D008565:Membrane Proteins / Q000302:isolation & purification / Q000378:metabolism*; D010446:Peptide Fragments / Q000032:analysis; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism*; D010786:Photoreceptor Cells / Q000378:metabolism*; D012374:Rod Cell Outer Segment / Q000378:metabolism*; D012969:Sodium Fluoride / Q000494:pharmacology*; D013873:Thionucleotides / Q000494:pharmacology; D015293:Transducin; D014357:Trypsin
chemical_list: D008565:Membrane Proteins; D010446:Peptide Fragments; D013873:Thionucleotides; D006165:Guanylyl Imidodiphosphate; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate; D012969:Sodium Fluoride; D010727:Phosphoric Diester Hydrolases; D014357:Trypsin; D015293:Transducin