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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 full length cDNA of two somatostatin receptors (SSTR2 and SSTR3) in the brain of Siniperca chuatsi was cloned by rapid amplification of cDNA ends (RACE). The full length cDNA of SSTR2 was 1 820 bp with an open reading frame of 1 146 bp encoding 382 amino acids. The full length of SSTR3 cDNA was 1 874 bp with an open reading frame of 1 458 bp encoding a protein of 486 amino acids. SSTR consists of five structural regions: N-terminal, 7 transmembrane domains (TMD), 3 extracellular ECLs, 4 intracellular ICLs and C-terminal. NJ phylogenetic tree analysis showed that SSTR2 and SSTR3 were relatively independent branches, the amino acid sequence similarity between the two was 51.2%, indicating that they are encoded by different genes. Tissue expression characteristics of SSTR2 and SSTR3 mRNA were detected by real-time fluorescence quantitative RT-PCR. They were widely expressed in many tissues. SSTR2 mRNA was highest in liver and SSTR3 mRNA was the highest in stomach. SSTR2, SSTR3 expression differences reflect their possible involvement in different physiological regulatory role.