中国人白细胞介素-12 cDNA基因的克隆及序列分析与比较

为研究中国人ＩＬ－１２的基因特征,采用逆转录巢式聚合酶链反应（ＲＴ－ｎＰＣＲ）从中国人脐带血单核细胞中分别克隆了Ｐ３５、Ｐ４０两亚基ｃＤＮＡ基因,包括完整的前体蛋白编码序列,其中Ｐ３５ ｃＤＮＡ编码２１９个氨基酸的多肽,Ｐ４０ ｃＤＮＡ编码３２８个氨基酸的多肽,与国外序列（ＮＫＳＦ、ＣＬＭＦ）比较结果发现：所克隆序列Ｐ３５同ＮＫＳＦ相比,第４４ａａ密友子由ＧＴＣ（Ｖａｌ）→ＧＴＧ（Ｖａｌ）,但未改

Cloning and Sequence Analysis of Chinese Interleukin 12 cDNA

In order to study the genetic characteristics of Chinese IL 12 gene, we cloned the cDNA genes of P40 and P35 subunits of IL 12 by RT nPCR from mononuclear cells of umbilical cord blood of a Chinese newborn, including the complete coding region of precursor protein, the nucleotide sequence was determined by the dideoxy mediated chain termination method. P35 cDNA sequence encodes a 219 amino acid polypeptide and P40 cDNA encodes a 328 amino acid polypeptide. Compared to the foreign sequences of NKSF, CLMF, we found that P35 sequence is different from that of NKSF, in which the 44 th amino acid codon changes to GTG(Val) from GTC(Val), but the deduced amino acid does not change. Compared to CLMF, 244 th amino acid codon GAC(Asp) changes to GAT(Asp), 247 th amino acid changes from Thr (ACG) to Met (ATG). Subunit P40 nucleotide sequence and deduced amino acids are identical with that of CLMF. However there are several differences between NKSF and P40: 239 th amino acid codon of P40 changes from AAC (Asn) to AAG (Lys), 291 th amino acid codon changes from ACC (Thr) to ACG (Thr). Sequence variations of these three are on the same nucleotide sites. The results indicate that although IL 12 gene is very conserved, its amino acid and nucleotide sequences have certain differences and the gene may be polymorphic. The IL 12 gene we cloned has some uniqueness.