Ward S B, Morrison S L
Department of Cellular and Molecular Biophysical Studies, Columbia University, New York, NY 10032.
Nucleic Acids Res. 1991 Dec 11;19(23):6475-80. doi: 10.1093/nar/19.23.6475.
The cell line G403.4.7, isolated as a spontaneous variant of the MPC-11 derived myeloma G403.4, produces a truncated gamma 2b HC protein, but no light chain (LC), and a single gamma 2b specific transcript of 2.4kb. This gamma 2b transcript consists of the VDJ and CH1 exons, the CH1 to Hinge (Hi) intervening sequence (IVS) and HI exon, part of the IVS between the two membrane exons M1 and M2, and most of the membrane 3' untranslated (UT) region. Even though the mature mRNA contains intronic sequences, it is abundant in the cytoplasm. Analysis of the gamma 2b genomic organization reveals that this unusual transcript results in part from two genomic deletions of 2.5kb and 588bp and in part from an altered splicing pattern. This altered splicing pattern is probably a consequence of the sequence alterations resulting from the genomic deletions. Analysis of these events provides some interesting insights into the mechanism of splice site selection and the evolution of introns and exons.
细胞系G403.4.7是从MPC - 11衍生的骨髓瘤G403.4自发变异而来，它产生一种截短的γ2b重链蛋白，但不产生轻链（LC），以及一个2.4kb的单一γ2b特异性转录本。这个γ2b转录本由VDJ和CH1外显子、CH1到铰链区（Hi）的间隔序列（IVS）和Hi外显子、两个膜外显子M1和M2之间IVS的一部分以及大部分膜3'非翻译（UT）区域组成。尽管成熟mRNA包含内含子序列，但它在细胞质中含量丰富。对γ2b基因组结构的分析表明，这种不寻常的转录本部分源于两个2.5kb和588bp的基因组缺失，部分源于改变的剪接模式。这种改变的剪接模式可能是基因组缺失导致的序列改变的结果。对这些事件的分析为剪接位点选择机制以及内含子和外显子的进化提供了一些有趣的见解。
