【摘要】 应用RT-PCR技术从香猪肝脏克隆到胰岛素样生长因子1(insulin-like growth factor 1,IGF-1)基因,共612bp,包含完整的开放读码框,与已知猪种的核苷酸相似性为99%~100%,编码的153个氨基酸包括信号肽、前体肽、B、C、A、D、E区,成熟肽仅由B到D区组成(70aa)。香猪IGF-1的氨基酸序列与长白猪完全一样,与淞辽黑猪相差一个氨基酸(E区);与人、犬、牛、马等的差异主要集中在信号肽、前体肽和E区,成熟肽完全相同;与小鼠的差异最大,成熟肽区有4个氨基酸不同,其他区域还有11个氨基酸不同。对香猪IGF-1成熟肽的三维结构分析结果显示,蛋白有3个α-螺旋,3对二硫键分别联系α-螺旋的N端和C端。对香猪IGF-1基因的组织分布研究结果显示,IGF-1基因在肝脏、脾、脂肪、软骨、肌肉、子宫组织中均有表达,其中肝脏的表达量最高;脊髓、肺中未检测到表达,提示IGF-1的旁分泌作用具有组织特异性。更多还原

【Abstract】 The complement DNA of insulin-like growth factor 1(IGF-1) was transcripted from the liver of Xiang pig breed by reverse transcription polymerase chain reaction(RT-PCR).The amplified fragments,612 bp,contained an open reading frame with similarity of 99%-100% to the known nucleotide sequences of IGF-1 from other pig breeds.The deduced amino acid sequence of IGF-1 precursor from Xiang pig breed consisted of signal,propeptide,mature peptide(including conserved B,C,A and D region) and E peptide which would be cut from the precursor.No difference in the precursor of IGF-1 between Xiang and Landrace breed was investigated,whereas one amino acid different in E peptide between Xiang and Song liao black pig breeds.The mature peptide sequences were conserved among pig,human,dog,cattle and horse with variation in the signal,propeptide and E peptide.The most divergent sequence of the mature peptide was found between Xiang pig and mouse with four amino acids variants except for eleven amido acids outside of the mature peptide of.It indicated that IGF-1 keep conserved in most of mammal animals except mouse.In the light of the three-dimensional models available for human IGF-1 mature peptide by NMR,the tertiary structures of IGF-1 from Xiang pig breed was characterized in three alpha-helixes with three pairs of disulfide bond linking the N-terminus and C-terminus of the three-helix.The tissue-specific expression of IGF-1 mRNA in Xiang pig was evaluated by RT-PCR.Levels of mRNA encoding IGF-1 protein were detected in liver and nonhepatic tissues(spleen,fat,cartilage,skeletal muscle,uterus) but not in spinal cord and lung.The performance of IGF-1 mRNA abundance in hepatic and nonhepatic tissues from Xiang pig breed supported the concept that IGF-1 plays important role on multiple tissues except for lung and spinal cord by parasecret pathway.更多还原