title: Properties of 1-methyladenine receptors in starfish oocyte membranes: involvement of pertussis toxin-sensitive GTP-binding protein in the receptor-mediated signal transduction.
abstract: In response to a meiosis-inducing hormone, 1-methyladenine (1-MA), starfish oocytes undergo reinitiation of meiosis with germinal vesicle breakdown. The 1-MA-initiated signal is, however, inhibited by prior microinjection of pertussis toxin into the oocytes, suggesting that a guanine nucleotide-binding protein (G protein) serving as the substrate of pertussis toxin is involved in the 1-MA receptor-mediated signal. We thus investigated properties of 1-MA receptors by means of binding of the radiolabeled ligand to the oocyte membranes. There were apparently two forms of 1-MA receptors with high and low affinities in the membranes. The high-affinity form was converted into the low-affinity one in the presence of a non-hydrolyzable analogue of GTP. A 39-kDa protein, which had been identified as the alpha-subunit of the major substrate G protein for pertussis toxin, was also ADP-ribosylated by cholera toxin only when 1-MA was added to the membranes. The ADP-ribosylated 39-kDa alpha-subunit could be immunoprecipitated with antibodies raised against the carboxy-terminal site of mammalian inhibitory G-alpha. These results indicate that 1-MA receptors are functionally coupled with the 39-kDa pertussis toxin-substrate G protein in starfish oocyte membranes.
authors.affiliation: Department of Life Science, Tokyo Institute of Technology, Yokohama, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Tadenuma
authors.forename: K
authors.initials: K
authors.lastname: Takahashi
authors.forename: K
authors.initials: K
authors.lastname: Chiba
authors.forename: M
authors.initials: M
authors.lastname: Hoshi
authors.forename: T
authors.initials: T
authors.lastname: Katada
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D000246:Adenosine Diphosphate Ribose / Q000378:metabolism; D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D002793:Cholic Acids / Q000494:pharmacology; D004229:Dithiothreitol / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D019204:GTP-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology*; D007700:Kinetics; D008970:Molecular Weight; D009243:NAD / Q000378:metabolism; D009865:Oocytes / Q000187:drug effects / Q000502:physiology*; D037342:Pertussis Toxin; D011506:Proteins / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D015398:Signal Transduction / Q000187:drug effects*; D013215:Starfish; D010566:Virulence Factors, Bordetella / Q000494:pharmacology*
chemical_list: C064996:1-methyladenine receptor; D002793:Cholic Acids; D011506:Proteins; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D010566:Virulence Factors, Bordetella; D009243:NAD; D000246:Adenosine Diphosphate Ribose; D016244:Guanosine 5'-O-(3-Thiotriphosphate); C008407:1-methyladenine; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins; D000225:Adenine; C028213:3-((3-cholamidopropyl)dimethylammonium)-1-propanesulfonate; D004229:Dithiothreitol