鳜两种生长抑素受体cDNA全长克隆与组织表达

Cloning and Expression of Two Somatostatin Receptor Genes in Siniperca chuatsi

利用cDNA末端快速扩增(RACE)技术克隆了鳜(Siniperca chuatsi)脑中2种生长抑素受体(somatostatin receptor,SSTR2和SSTR3)cDNA全长序列。结果显示,鳜SSTR2 cDNA全长1 820 bp,含开放阅读框1 146 bp,编码382个氨基酸;SSTR3 cDNA全长1 874 bp,含开放阅读框1 458 bp,编码486个氨基酸。SSTR均由5个结构区域组成:N端、7个转膜区(TMD)、3个细胞外袢(ECLs)、4个细胞内袢(ICLs)和C末端。NJ系统进化树分析显示,鳜SSTR2和SSTR3分别形成相对独立的分支,两者间的氨基酸序列相似度为51.2%,表明它们是由不同基因编码而成。利用实时荧光定量RT-PCR技术检测了鳜SSTR2和SSTR3 mRNA的组织表达特征,它们均在多种组织中广泛表达,SSTR2 mRNA在肝中表达量最高,SSTR3 mRNA在胃中表达量最高。SSTR2、SSTR3表达差异反映它们可能参与不同生理调控作用。

The complete eDNA sequences of two distinct somatostatin receptor genes （SSTR2 and SSTR3） were isolated from Siniperca chuatsi brain and cloned by means of rapid amplification of eDNA ends （RACE）. The full length of SSTR2 eDNA was 1 820 bp, containing 1 146 bp open reading frame and encoding 382 amino acids,whereas the full length of SSTR3 eDNA was 1 874 bp, containing 1 458 bp open reading frame and encoding 486 amino acids. Five domains were detected in SSTRs： the N-terminal domain, seven putative transmembrane domains （TMD） , three extraeellular loops （ECLs） , four intracellular loops （ICLs） and the C- terminal domain. NJ phylogenetie tree showed that SSTR2 and SSTR3 formed two independent branches,and that the amino acid sequence similarity between SSTR2 and SSTR3 was 51.2% , which indicated that they were encoded by two different genes. A wide tissue expression of SSTR2 and SSTR3 mRNA were revealed by real- time quantitative RT-PCR,with the highest expression of SSTR2 mRNA in liver,and SSTR3 mRNA in stomach, suggesting that they may be involved in different physiological regulations.