title: Solubilization of membrane-bound rod phosphodiesterase by the rod phosphodiesterase recombinant delta subunit.
abstract: Retinal rod and cone phosphodiesterases are oligomeric enzymes that consist of a dimeric catalytic core (alpha'2 in cones and alphabeta in rods) with inhibitory subunits (gamma) that regulate their activity. In addition, a 17-kDa protein referred to as the delta subunit co-purifies with the rod soluble phosphodiesterase and the cone phosphodiesterase. We report here partial protein sequencing of the rod delta subunit and isolation of a cDNA clone encoding it. The predicted amino acid sequence is unrelated to any other known protein. Of eight bovine tissue mRNA preparations examined by Northern analysis, the strongest delta subunit-specific signal was present in the retina. A less intense signal was seen in the brain and adrenal mRNA. In bovine retinal sections, rod delta subunit anti-peptide antibodies label rod but not cone outer segments. delta subunit, added back to washed outer segment membranes, solubilizes a large fraction of the membrane-bound phosphodiesterase, indicating that this subunit binds to the classical membrane associated phosphodiesterase. The subunit forms a tight complex with native, but not trypsin-released phosphodiesterase, suggesting that the isoprenylated carboxyl termini of the catalytic subunits may be involved in binding of the delta subunit to the phosphodiesterase holoenzyme.
authors.affiliation: Department of Pharmacology, University of Washington School of Medicine, Seattle, Washington 98195-7280, USA.
authors.forename: S K
authors.initials: SK
authors.lastname: Florio
authors.forename: R K
authors.initials: RK
authors.lastname: Prusti
authors.forename: J A
authors.initials: JA
authors.lastname: Beavo
mesh_terms: D015106:3',5'-Cyclic-GMP Phosphodiesterases / Q000737:chemistry* / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002417:Cattle; D002451:Cell Compartmentation; D002462:Cell Membrane / Q000201:enzymology; D003001:Cloning, Molecular; D054707:Cyclic Nucleotide Phosphodiesterases, Type 6; D018076:DNA, Complementary / Q000235:genetics; D005136:Eye Proteins / Q000737:chemistry* / Q000235:genetics; D015870:Gene Expression; D007158:Immunologic Techniques; D046911:Macromolecular Substances; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D017924:Nucleopolyhedroviruses; D010727:Phosphoric Diester Hydrolases / Q000737:chemistry* / Q000235:genetics; D012333:RNA, Messenger / Q000235:genetics; D017948:Retinal Rod Photoreceptor Cells / Q000201:enzymology; D012374:Rod Cell Outer Segment / Q000201:enzymology*; D012995:Solubility; D018411:Spodoptera; D014018:Tissue Distribution; D014785:Vision, Ocular
chemical_list: D018076:DNA, Complementary; D005136:Eye Proteins; D046911:Macromolecular Substances; D012333:RNA, Messenger; D010727:Phosphoric Diester Hydrolases; D015106:3',5'-Cyclic-GMP Phosphodiesterases; D054707:Cyclic Nucleotide Phosphodiesterases, Type 6