大熊猫生长激素受体(GHR)cDNA的克隆与序列分析

根据已报道的若干物种GHR 基因cDNA 序列设计引物, 利用RT- PCR 技术首次从大熊猫肝脏组织总RNA中扩增出GHR 基因编码区全长cDNA 序列, 克隆于pGEM®-T 载体后进行测序和序列分析。结果表明,大熊猫GHR 的ORF为1 917 bp , 编码638 个氨基酸的前体蛋白, 由18 个氨基酸的信号肽和620 个氨基酸的成熟肽组成,与人、狗、猪GHR 结构相似, 大熊猫GHR 成熟肽由246 个氨基酸的胞外区、24 个氨基酸的跨膜区和350 个氨基酸的胞内区组成, 并具GHR 的特征性结构。序列相似性比较显示, 大熊猫GHR 与哺乳类GHR 具有69 %～93 %的高序列相似性, 与爬行类和鸟类的序列相似性也达到60 % , 而与鱼类的序列相似性较低, 仅为30 %左右。与其它哺乳动物GHR 相比, 大熊猫GHR 在氨基酸序列上也存在明显的特异性。

cDNA Cloning and Sequence Analysis of Growth Hormone Receptor (GHR) from Giant Panda

The gene encoding giant panda (Ailuropoda melanoleuca) growth hormone receptor (GHR) was amplified by RT-PCR from the liver total RNA. Cloned into pGEM ~(R -T vector, the PCR product was sequenced and analyzed subsequently. The results indicated that the open reading frame (ORF) of giant panda GHR is 1 917 bp, which encodes a 638 amino acid precursor containing a signal peptide of 18 amino acids and a mature peptide of 620 amino acid.Mature GHR of giant panda possesses similar GHR architectural structure from human, dog,and pig, all including a 246 amino acids extracellular domain, a hydrophobic transmembrane region of 24 amino acid followed by a 350 amino acid cytoplasmic region,and all conserved landmarks of GHR were also found in giant panda GHR from sequence alignment. Sequence analysis revealed a fairly high similarity between giant panda GHR and GHR from mammals ranging from 69% to 93%, and a medium level similarity of 60% with the birds and reptiles.But the amino acid similarity decreases to only 30% for fish species.Despite the great similarity, giant panda GHR has its own specificity in the amino acid compared to GHR from other mammals, suggesting possible difference on biological function.