Molecular characteristics of growth hormone gene in yak

Growth hormone is a single-chain polypeptide hormone and secreted by anterior pituitary.GH exist in a wide variety of vertebrates,it can promote animal growth and development.The objective of this study was to clone the yak GH gene and do sequence analysis.A pair of specific PCR primers were designed for cloning the coding sequence of GH gene from pituitary tissue in yak.A fragment with 654 bp was got by RT-PCR amplifying,in which included a complete open reading frame and it encoded 217 amino acids(GeneBank accession No.EF154193).Bioinformatics analysis of the molecular characteristics showed that the growth hormone gene was very conservative.Compared nucleotide sequence with cattle,there was only a base difference,which the 607th base was A in yak,but C in cattle,and this difference did not led to amino acid change,and both encoded Arg.The amino acids sequences of yak shared 100 %,99.1 %,98.6 %,88.9 %,88.5 %,88.9 % and 89.4 % sequence similarity with cattle,goat,sheep,horse,pig,cat and dog respectively;the protein had two obvious hydrophobic region,existence of two strong transmembrane region and signal peptide.The protein second structure main was α-helix and irregular curly and three-dimensional solution structure composed of 28-215 amino acids.Yak growth hormone protein had higher antigenic index and higher lymphocyte epitopes,which was consistent with of the higher antigenicity of YGH coding protein.