用单抗5C5和5C5-G1筛选的613bp cDNA的核苷酸序列分析

A 613bp cDNA screened from a human tonsil lambda gtll cDNA library by a mixture of McAb 5C5 and 5C5-G1

用识别人活化B细胞分化抗原５Ｃ５的单克隆抗体５Ｃ５和５Ｃ５－Ｇ１的混合物从人扁桃体细胞λｇｔ１１ｃＤＮＡ文库筛选到３个阳性克隆。其ｃＤＮＡ插入到质粒ｐＵＣ１８，经双链双脱氧测序法作核苷酸序列分析，知其中一个ｃＤＮＡ长６１３ｂｐ，另二个长４６７ｂｐ，后者与前者的前４６７ｂｐ完全重叠。６１３ｂｐｃＤＮＡ中有一个开放阅读框架，从１０３ｂｐ到４２９ｂｐ，共３２７ｂｐ。Ｎｏｒｔｈｅｒｎ印迹分析显示，此６１３ｂｐ ｃＤＮＡ与人扁桃体细胞和３Ｄ５细胞的ＲＮＡ在２．０ｋｂ左右有杂交带。与国际上有关基因库的资料比较，未发现有任何同源核苷酸序列。由于这是一个新的ｃＤＮＡ序列，ＧｅｎＢａｎｋ已接受（接受号为Ｕ２５０４１）。从此ｃＤＮＡ的读框推断的蛋白质中第２０－３０氨基酸为明显的疏水区，故这个蛋白有典型的膜蛋白结构。

positive clones have been obtained from a human tonsil cell lambda gt 11 cDNA library screened with a mixture of McAb 5C5 and 5C5-G1 . The cDNAs of the positive clones were inserted into plasmid pUC1 8. The cDNAs were sequenced with . dideoxy-necleotide chain termination method. One cDNA was 613bp long and the length of the other two were 467bp. The latter overlapped the first 467bp of the former completely. There existed an open reading frame of 327bp (from 103bp to 429bp ) in the 6 1 3bp cDNA, Northern blot analysis revealed that the 6 1 3bp cDNA hybridized the RNA extracted from human tonsil cells or 3D5 cells at the site around 2. 0kb. The sequence of the cDNA is not homologous to any DNA saquence published in the world , hance has been accessioned by GenBank with a accessed number of U25041. In the protein deduced from the nucleotide sequence there existed a hydrophobic region from amino acid residue 20 to 30.