Cloning and sequencing of full length growth hormone cDNA from Lepomis cyanellus

The full length cDNA encoding growth hormone of a freshwater f ish, Lepomis cyanellus, (LcGH) was cloned from pituitary RNA with RT-PCR, 3..and 5.. RACE ( rapid amplif ication of cDNA ends) . The LcGH cDNA ( Genbank No. AY530822) , about 989nt ( nucleotide) long, consisted of a open reading frame with 615nt long, 5..and 3..untranslated regions with 93nt and 224nt long respectively, and a 57nt poly ( A) tail. The DNA sequence analysis showed that there are typical Kozak sequence and polyadenylation signal. The pregrowth hormone peptide of 204aa deduced from LcGH cDNA included a putative signal peptide ( 17aa) locating in its Nterminal. There exist a Asn-Cys-Thr glycosylation site at amino acid 201, and 4 cysteine residues ( No. 69, 177, 194, 202) that are essential to construct two S-S bonds in this pregrowth hormone peptide. Homological comparision among LcGH and other species growth hormones showed that There is high homology ( more than 85% ) between growth hormone of Lepomis cyanellus and that of most perciformes fish, but low homology ( less than 70%) in comparison with other species such as Siluriformes and Cypriniformes f ish.