Mounir S, Guglielmi P, Preud'homme J, Nau F, Cogné M
Laboratoire d'Immunologie Moléculaire, (CNRS URA 1172), Faculté des Sciences, Poitters, France.
J Immunol. 1990 Jan 1;144(1):342-7.
The Burkitt's lymphoma cell lines JBL2 and Ly91 contain intracytoplasmic mu chains without L chain by immunofluorescence. These mu chains and the corresponding cDNA are abnormally short. Detailed analysis of the productive H chain alleles showed that the cell lines JBL2 and Ly91 use a VHIV and a VHIII subgroup gene, respectively. In both cell lines, the 3' part of the V exon was markedly abnormal and contained several stop codons. Point mutations affected the JH6 donor splice site in the JBL2 gene, precluding normal splicing into C mu. Although the JH2 splice site was unmodified in Ly91, it was not used. As in JBL2, splicing occurred at an alternate splice site present 5' of these alterations, thus removing all these abnormalities from the mature transcripts. This alternate splicing explains the presence in both cell lines of truncated mRNA and proteins lacking two-thirds of the V region.
通过免疫荧光法检测发现，伯基特淋巴瘤细胞系JBL2和Ly91含有无轻链的胞质内μ链。这些μ链及相应的cDNA异常短。对有功能的重链等位基因的详细分析表明，细胞系JBL2和Ly91分别使用VHIV和VHIII亚组基因。在这两个细胞系中，V外显子的3'部分明显异常，含有多个终止密码子。点突变影响了JBL2基因中的JH6供体剪接位点，阻止其正常剪接至Cμ。尽管Ly91中的JH2剪接位点未被修饰，但未被使用。与JBL2一样，剪接发生在这些改变位点5'端的一个替代剪接位点，从而从成熟转录本中去除了所有这些异常。这种替代剪接解释了两个细胞系中均存在截短的mRNA和缺少三分之二V区的蛋白质的原因。
