title: Molecular cloning of a putative receptor guanylyl cyclase from Y-organs of the blue crab, Callinectes sapidus.
abstract: Crustacean molt-inhibiting hormone (MIH), a polypeptide produced by neurosecretory cells in eyestalk ganglia, suppresses the synthesis of ecdysteroid molting hormones by paired Y-organs. Data from several sources indicate the effects of MIH are mediated, at least in part, by a cGMP second messenger. Based on these and related findings, our working hypothesis is that the MIH receptor is a receptor guanylyl cyclase (rGC). In studies reported here, we used a PCR-based cloning strategy (RT-PCR followed by 5'- and 3'-RACE) to clone from blue crab (Callinectes sapidus) Y-organs a cDNA (CsGC-YO1) encoding a putative rGC. DNA sequence analysis revealed a 3807 base pair open reading frame encoding a 56 residue signal peptide and a 1213 residue rGC. Analysis of the deduced amino acid sequence showed that CsGC-YO1 contains the signature domains characteristic of rGCs, including an extracellular ligand-binding domain, a single transmembrane domain, a kinase-like domain, a dimerization domain, and a cyclase catalytic domain. CsGC-YO1 is most closely related to an rGC from the crayfish, Procambarus claikii (PcGC-M2, 58.4% identity), and rGCs from three insect species (33.1-37.5% identity). Conserved cysteine residues are similarly distributed in the extracellular domains of CsGC-YO1, PcGC-M2, and the three insect rGCs. RT-PCR revealed the CsGC-YO1 transcript is expressed in Y-organs and several other tissues. While other interpretations of the data are possible, our working hypothesis is that the cloned cDNA encodes an MIH receptor.
authors.affiliation: Department of Biology, University of Alabama at Birmingham, AL 35294, USA.
authors.forename: Junying
authors.initials: J
authors.lastname: Zheng
authors.forename: Chi-Ying
authors.initials: CY
authors.lastname: Lee
authors.forename: R Douglas
authors.initials: RD
authors.lastname: Watson
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003386:Brachyura / Q000502:physiology*; D004702:Endocrine Glands / Q000502:physiology*; D006162:Guanylate Cyclase / Q000235:genetics* / Q000502:physiology; D007447:Invertebrate Hormones / Q000502:physiology; D008969:Molecular Sequence Data; D010802:Phylogeny
chemical_list: D007447:Invertebrate Hormones; C012445:molt-inhibiting hormone; D006162:Guanylate Cyclase