title: Cloning and characterization of cDNAs encoding the GnRH1 and GnRH2 precursors from bullfrog (Rana catesbeiana).
abstract: We have isolated the cDNAs encoding the GnRH1 and GnRH2 precursors, respectively, from bullfrog (Rana catesbeiana) brain. The first cDNA consists of 648 bp and contains an open-reading frame of 270 nucleotides, encoding the bullfrog GnRH1 precursor. The second cDNA consists of 1053 bp and contains an open-reading frame of 255 nucleotides, encoding the bullfrog GnRH2 precursor. Both types of bullfrog GnRH precursor have a similar molecular architecture as observed in other GnRH precursors, consisting of a signal peptide, followed by the GnRH decapeptide, a conserved carboxy-terminal amidation and proteolytical processing site, and a GnRH-associated peptide (GAP). In addition, we have identified a third cDNA, containing 24 additional nucleotides in its GAP-coding region. Genomic PCR and sequence analysis confirmed that this cDNA represents an alternative splice variant of the bullfrog GnRH2-precursor pre-mRNA. The bullfrog GnRH1 precursor exhibits 60% and less than 40% amino acid identity to its Xenopus and mammalian counterparts, respectively, whereas the bullfrog GnRH2 precursor displays 50% to 60% amino acid identity to that of its nonmammalian counterparts, but shares only 25% amino acid identity with its mammalian counterparts. Northern blot analysis revealed a single GnRH1-precursor mRNA species of approximately 0.75 kilobases, expressed in bullfrog forebrain, and a single GnRH2-precursor mRNA species of approximately 1.1 kilobases, expressed in bullfrog midbrain/hindbrain. Furthermore, both bullfrog GnRH-precursor mRNAs exhibited a differential spatiotemporal expression pattern. Genomic Southern blot analysis indicated that both bullfrog GnRH genes are present as single copy genes. This is the first report on the molecular cloning of a GnRH2-precursor cDNA from an amphibian species. In addition, we present data showing that alternative splicing is utilized to generate different GnRH2-precursor mRNAs. J. Exp. Zool. 289:190-201, 2001.
authors.affiliation: Hormone Research Center and Department of Biology, Chonnam National University, Kwangju 500-757, Republic of Korea.
authors.forename: L
authors.initials: L
authors.lastname: Wang
authors.forename: M S
authors.initials: MS
authors.lastname: Yoo
authors.forename: H M
authors.initials: HM
authors.lastname: Kang
authors.forename: W B
authors.initials: WB
authors.lastname: Im
authors.forename: H S
authors.initials: HS
authors.lastname: Choi
authors.forename: J
authors.initials: J
authors.lastname: Bogerd
authors.forename: H B
authors.initials: HB
authors.lastname: Kwon
mesh_terms: D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern; D001921:Brain / Q000378:metabolism; D003001:Cloning, Molecular; D018076:DNA, Complementary; D020869:Gene Expression Profiling; D007987:Gonadotropin-Releasing Hormone / Q000031:analogs & derivatives* / Q000145:classification / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny; D011498:Protein Precursors / Q000235:genetics*; D011892:Rana catesbeiana; D017386:Sequence Homology, Amino Acid
chemical_list: D018076:DNA, Complementary; D011498:Protein Precursors; D007987:Gonadotropin-Releasing Hormone