Cloning, Expression And Sequence Analysis Of Gonadotropin Subunits CDNA In The Bighead Carp (Hypophthalmichthys Nobilis)

Gonadotropin(GtH) is a glycoprotein hormone that is synthesized by vertebrates Pituitary regulates gonad development and sex maturation.In teleost fish,there are two forms of GtHs,and in other vertebrates also, traditionally referred to as GtH-Ⅰand GtH-Ⅱ,which are believed to be FSH-like and LH-like,respectively.GtHs are dimeric glycoprotein hormones composed of a common alpha subunit and two hormone-specificβsubunits,which confers its biological specificity.The hormonal activity is expressed only after a non-covalent association between these two subunits.The complete sequences of the bighead carp(Hypophthalmichthys nobilis)GTH subunits(GTHα,LHβ,FSHβ) were determined by rapid amplification of cDNA ends(RACE) and nucleotide sequencing.Based on the bio-software analysis,the cDNA of GTHα(Accession NO.EU095937) consisted 839bp nucleotides encoding peptides 118 amino acids,which is preceded by 23 aa signal peptide,433bp 3'-untranslated region(UTR).,The cDNA of FSHβ(Accession NO.EF552360) consisted 645bp nucleotides encoding peptides 131 amino acids,which is preceded by 23 aa signal peptide,130 bp 5'-untranslated region(UTR) and 118 bp 3'-untranslated region(UTR).The cDNA of LHβ(Accession NO. EF565164) consisted 559 bp nucleotides encoding peptides 147 amino acids,which is preceded by 31 aa signal peptide,114 bp 3'-untranslated region(UTR).The mature peptides of bighead carp GTHα,LHβ,FSHβshowed hige sequence identities(GTHα70%-99%,LHβ53%-97%,FSHβ38%-93%) and LH-βsubunit was higher conservative than FSHβsubunit in bighead carp.Expression analysis by RT-PCR showed that GTHβsubunits could be only expressed in pituitary.Through the analysis of ANTHEPROT5.0,the result show the molecular weight of FSHβis 14.7KDa,LHβis 16.5KDa,GTHαis 14.7KDa.The majority of the secondary structures of FSHβis turn,LHβis turn and sheet,GTHαis helix and turn.