Cogné M, Preud'homme J L
CNRS URA 1172, Faculté des Sciences, Poitiers, France.
J Immunol. 1990 Oct 15;145(8):2455-8.
We studied a case of nonsecretory alpha-chain disease. The proliferating plasma cells contained a short transcript coding for a truncated membrane-form alpha 1-chain. The productive alpha-gene bore several noncontiguous deletions affecting the VHDJH and CH1 regions. Two deletions were accompanied with peculiar insertions containing duplications. The first insertion contained an acceptor splice site and was present in part in the mature transcript, thus coding for an abnormal aminoterminal peptide. Another deletion located 3' to CH3 eliminated the polyadenylation site of secreted-form alpha-mRNA. As a result, only membrane-form alpha mRNA was present in the tumoral plasma cells, thus explaining the nonsecretory phenotype of the disease. Comparison of cDNA and genomic sequences showed that the previously undescribed human alpha membrane region is encoded by a single exon, beginning with two alternate acceptor splice sites, and comprises either 65 or 71 amino acids.
我们研究了一例非分泌型α链病。增殖的浆细胞含有一个编码截短膜形式α1链的短转录本。有功能的α基因存在几个影响VHDJH和CH1区域的非连续缺失。两个缺失伴有包含重复序列的特殊插入。第一个插入含有一个剪接受体位点，部分存在于成熟转录本中，因此编码一个异常的氨基末端肽。另一个位于CH3下游3'处的缺失消除了分泌型α-mRNA的聚腺苷酸化位点。结果，肿瘤性浆细胞中仅存在膜形式α mRNA，从而解释了该疾病的非分泌表型。cDNA和基因组序列的比较表明，先前未描述的人类α膜区域由单个外显子编码，起始于两个交替的剪接受体位点，包含65或71个氨基酸。
