title: Cloning and characterization of a cDNA coding for the alpha-subunit of a stimulatory G protein from Schistosoma mansoni.
abstract: Guanine nucleotide-binding proteins (G proteins) mediate signals between serotonin receptors and adenylate cyclase in Schistosoma mansoni. A bovine Gs alpha cDNA probe was used to isolate a cDNA clone, SG12, encoding the entire alpha-subunit of a G protein of S. mansoni. The cDNA is 1897 base pairs long, contains an open reading frame of 1137 base pairs, and codes for a deduced protein of 379 amino acids. The putative protein encoded by the clone has an exact amino acid match with bovine Gs alpha of 65% and a 78% match when conserved amino acid substitutions are considered. In contrast, the exact and conserved matches of the schistosome alpha-subunit with bovine Gi are 41 and 61%, respectively. A comparison of the deduced amino acid sequence of SG12 with a variety of different G alpha proteins indicates that all the major structural features characteristic of a Gs alpha protein are present in the S. mansoni gene. The schistosome clone contains the putative site for ADP-ribosylation by cholera toxin found in Gs alpha but does not contain the ADP-ribosylation site for pertussis toxin present in Gi alpha. The amino acids are completely conserved at the GTP-binding sites. On a Northern blot, the cDNA hybridizes to a major band of 3.1 kilobases in RNA from adult schistosomes. The message appears to be absent in miracidia and cercariae, but a faint 3.1-kilobase band is visible in the early schistosomule stage preceding adulthood. This evidence, when added to previous biochemical data, indicates that the expression of this gene is developmentally controlled.
authors.affiliation: Department of Pharmacology, Stanford University School of Medicine, California 94305.
authors.forename: M H
authors.initials: MH
authors.lastname: Iltzsch
authors.forename: D
authors.initials: D
authors.lastname: Bieber
authors.forename: S
authors.initials: S
authors.lastname: Vijayasarathy
authors.forename: P
authors.initials: P
authors.lastname: Webster
authors.forename: M
authors.initials: M
authors.lastname: Zurita
authors.forename: J
authors.initials: J
authors.lastname: Ding
authors.forename: T E
authors.initials: TE
authors.lastname: Mansour
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016375:Antisense Elements (Genetics); D001483:Base Sequence; D002417:Cattle; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics* / Q000302:isolation & purification; D015342:DNA Probes; D004330:Drosophila / Q000235:genetics; D019204:GTP-Binding Proteins / Q000235:genetics* / Q000302:isolation & purification; D015723:Gene Library; D046911:Macromolecular Substances; D008297:Male; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009838:Oligodeoxyribonucleotides; D012313:RNA / Q000235:genetics / Q000302:isolation & purification; D015347:RNA Probes; D015183:Restriction Mapping; D012550:Schistosoma mansoni / Q000235:genetics* / Q000378:metabolism; D012689:Sequence Homology, Nucleic Acid
chemical_list: D016375:Antisense Elements (Genetics); D015342:DNA Probes; D046911:Macromolecular Substances; D009838:Oligodeoxyribonucleotides; D015347:RNA Probes; D012313:RNA; D004247:DNA; D019204:GTP-Binding Proteins