文章基本信息

标题：Tyrosine phosphorylation of components of the B-cell antigen receptors following receptor crosslinking.
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作者：M R Gold ; L Matsuuchi ; R B Kelly 等
期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1991
卷号：88
期号：8
页码：3436-3440
DOI：10.1073/pnas.88.8.3436
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Crosslinking membrane immunoglobulin (mIg), the B-cell antigen receptor, stimulates tyrosine phosphorylation of a number of proteins. Since many receptors are phosphorylated after ligand binding, we asked if components of the mIg receptor complexes were tyrosine-phosphorylated after mIg crosslinking. Both mIgM and mIgD are noncovalently associated with at least two other proteins. mIgM is associated with the MB-1 protein, which is disulfide-linked to a protein designated Ig-beta. mIgD is not associated with MB-1 but is with IgD-alpha, which is also disulfide-linked to Ig-beta. Using immunoprecipitation with a specific anti-MB-1 antiserum followed by anti-phosphotyrosine immunoblotting, we found that crosslinking mIgM stimulated tyrosine phosphorylation of MB-1, Ig-beta, and a previously unidentified 54-kDa polypeptide associated with MB-1. In mature splenic B cells that express both mIgM and mIgD, mIgM crosslinking stimulated tyrosine phosphorylation of the 32-kDa MB-1 protein, whereas mIgD crosslinking stimulated tyrosine phosphorylation of MB-1-related proteins of 33 and 34 kDa. The 32-kDa MB-1 protein was only associated with mIgM, whereas the 33- and 34-kDa MB-1-related proteins were specifically associated with mIgD and are most likely IgD-alpha. Thus, crosslinking either mIgM or mIgD stimulated tyrosine phosphorylation only of the MB-1-related proteins associated with that receptor.