Koyama M, Nakamura T, Higashihara M, Herren B, Kuwata S, Shibata Y, Okumura K, Kurokawa K
First Department of Internal Medicine, University of Tokyo, Japan.
Immunol Lett. 1995 Sep;47(3):151-6. doi: 10.1016/0165-2478(95)00071-x.
The Ig-alpha/Ig-beta heterodimers encoded by mb-1 and B29 genes, respectively, are crucial for the constitution of the B-cell receptor (BCR). We report here novel variants of mb-1 and B29 transcripts produced by alternative mRNA splicing. The proteins encoded by these variants are predicted to conserve transmembrane and cytoplasmic portions of Ig-alpha and Ig-beta but lack a part of the extracellular portions containing cysteine residues which are required for intramolecular and intermolecular S-S bonds. Transfection studies revealed that the variant mb-1 and B29 did not contribute to the BCR expression on cell surfaces. Although peripheral B cells contain small amounts of the variant mb-1 and B29 transcripts, treatment with an anti-IgM antibody, LPS or IL-4 induces a significant increase in amounts of the variant transcripts. These observations suggest that B-cell activation induces alternative splicing of mb-1 and B29 transcripts which encode proteins unable to constitute the BCR.
分别由mb-1和B29基因编码的Ig-α/Ig-β异二聚体对于B细胞受体（BCR）的构成至关重要。我们在此报告了通过可变mRNA剪接产生的mb-1和B29转录本的新型变体。这些变体编码的蛋白质预计保留Ig-α和Ig-β的跨膜和胞质部分，但缺少包含分子内和分子间S-S键所需的半胱氨酸残基的部分细胞外部分。转染研究表明，变体mb-1和B29对细胞表面BCR的表达没有贡献。尽管外周B细胞含有少量的变体mb-1和B29转录本，但用抗IgM抗体、LPS或IL-4处理会导致变体转录本的量显著增加。这些观察结果表明，B细胞活化诱导了mb-1和B29转录本的可变剪接，这些转录本编码无法构成BCR的蛋白质。
