鹅白细胞介素 2基因的克隆与分子模型

对鸡、鸭、火鸡IL-2的核苷酸序列进行比较，在其保守区设计引物，通过RT-PCR方法扩增和克隆了鹅白介素2 (goIL-2) 的核苷酸序列。该序列由768 nt组成，编码一条由141个氨基酸组成的前体蛋白。goIL-2核苷酸序列和氨基酸序列与鸭IL-2(duIL-2)核苷酸序列和氨基酸序列的同源性为90.1%和83.6%，与鸡、火鸡和鹌鹑IL-2的同源性为69.7%-75%和61.0%-63.1%，与哺乳动物IL-2的同源性为25%-30%和14%-17%。氨基酸序列分析表明，N端存在一长21个氨基酸的信号肽，含有形成2个链内二硫键的4个半胱氨酸。goIL-2 mRNA的体外表达动力学分析表明，脾脏T淋巴细胞经Con A诱导2 h至24 h均可检测到goIL-2 mRNA的表达。三维结构预测表明，goIL-2蛋白由A、B、C、D 4个α-螺旋和2个?-折叠构成。遗传进化分析表明，goIL-2和duIL-2的亲缘关系最近。

Cloning and molecular model of goose interleukin-2

cDNA encoding goose IL-2 (goIL-2) was cloned from Con A-stimulated goose SMC using oligonucleotide primers based on the conserved sequence of duck IL-2 (duIL-2), chicken IL2 (chIL-2) and turkey IL-2 (TuIL-2). Sequencing results showed that the goIL-2 nucleotide sequence was 768 bp in length, encoding a polypeptide of 141 amino acid residues. The predicted nucleic acid and amino acid sequences of goIL-2 were of 90.1% and 83.6% identical to duIL-2, 69.7%-75% and 61.0%-63.1% to chIL-2, tuIL-2 and quail IL-2, 25%-30% and 14%-17% with mammalian IL-2s, respectively. Amino acid sequence analysis showed that the predicted protein had a leader sequence composed of 21 amino acids, and four conserved cysteines allowing the formation of two intrachain disulfide bonds. GoIL-2 mRNA was detectable using RT-PCR assay in goose splenic mononuclear cells from 2 h to 24 h after stimulation. Three-dimensional structure prediction indicated that the mature goose IL-2 protein contained A, B, C and D four α-helix bundle structures and two β-sheets. Phylogenetic analysis showed that the goIL-2 had close relationship with duIL-2 and had distant relationship with tuIL-2.