Schiff C, Milili M, Zucman-Rossi J, Djabali M, Fougereau M
Centre d'Immunologie de Marseille Luminy (CIML), Case 906, 13288 Marseille Cedex 09 France.
Mamm Genome. 1996 Aug;7(8):598-602. doi: 10.1007/s003359900177.
The surrogate light chain, composed of the VpreB and the lambda-like proteins, plays a critical role in controlling the early stages of B lymphocyte development. The lambda-like locus, located on the q11. 2-q11.3 region of human Chromosome (Chr) 22, contains three genes (14.1 Flambda-1, and 16.1) among which only the 14.1 is functional. This gene contains three exons, whereas the others lack exon 1. We have isolated in fetal liver a transcript of the Flambda-1 gene that contains the exon 3 sequence and a long non-Ig related sequence upstream. We show that this sequence resulted from the splicing of three new exons located telomeric to the Flambda-1 gene, highly homologous to beta-glucuronidase exon 11 (Chr 7), to the ABR exon 8 (Chr 17), and to an Expressed Sequence Tag (EST), respectively. We also show that this chimeric transcript is expressed in cells or tissues from various origins. This composite gene structure appears to be a new example of human genome flexibility, which can be explained by mechanisms such as exon shuffling and which results in the emergence of new transcription units inserted in regions involved in translocations.
替代轻链由VpreB和类λ蛋白组成，在控制B淋巴细胞发育的早期阶段发挥关键作用。类λ基因座位于人类22号染色体（Chr）的q11.2 - q11.3区域，包含三个基因（14.1、Flambda - 1和16.1），其中只有14.1具有功能。该基因包含三个外显子，而其他基因缺乏外显子1。我们在胎儿肝脏中分离出了Flambda - 1基因的一个转录本，它包含外显子3序列以及上游一段长的非免疫球蛋白相关序列。我们发现该序列是由位于Flambda - 1基因端粒侧的三个新外显子剪接而成，它们分别与β - 葡萄糖醛酸酶外显子11（7号染色体）、ABR外显子8（17号染色体）和一个表达序列标签（EST）高度同源。我们还发现这种嵌合转录本在各种来源的细胞或组织中都有表达。这种复合基因结构似乎是人类基因组灵活性的一个新例子，这可以通过外显子洗牌等机制来解释，其结果是在涉及易位的区域出现了新插入的转录单元。
