IGM ANTIGEN RECEPTOR COMPLEX CONTAINS PHOSPHOPROTEIN PRODUCTS OF B29 AND MB-1 GENES
IGM ANTIGEN RECEPTOR COMPLEX CONTAINS PHOSPHOPROTEIN PRODUCTS OF B29 AND MB-1 GENES
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DOI：
10.1073/pnas.88.9.3982
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发表时间：
1991-05-01
影响因子：
11.1
通讯作者：
CAMBIER, JC
中科院分区：
文献类型：
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作者：
CAMPBELL, KS;HAGER, EJ;CAMBIER, JC
膜免疫球蛋白M(MIgM)和mIgD是主要的B淋巴细胞抗原受体，它们的功能是内化抗原，将抗原加工和呈递给T细胞，并传递增殖和分化所需的信号。尽管mIgM或mIgD的连接导致磷脂酶C和酪氨酸激酶(S)的快速激活，但这些受体的细胞质尾部只有三个氨基酸残基(Lys-Val-Lys)，似乎不适合与细胞质信号转导结构的直接物理耦合。在这份报告中，我们确定了mIgM相关磷酸蛋白复合体的α、β和伽马成分，它们可能在信号转导中发挥作用。蛋白水解肽图谱显示，IgM-α链不同于Ig-β和Ig-γ。这些链被纯化，氨基末端测序显示与先前克隆的两个B细胞特异性基因具有同源性。其中一种成分是IgM-α，是mb-1基因的产物，另外两种成分Ig-β和Ig-Gamma是B29基因的产物。用针对每个基因产物预测的肽序列制备的兔抗体的免疫印迹分析证实了这些mIgM相关蛋白的鉴定。推测的序列表明，这些受体亚基缺乏固有的蛋白激酶结构域，但包括共同的含有酪氨酸的序列基序，这些基序可能是诱导酪氨酸磷酸化的部位。
Membrane immunoglobulin M (mIgM) and mIgD are major B-lymphocyte antigen receptors, which function by internalizing antigens for processing and presentation to T cells and by transducing essential signals for proliferation and differentiation. Although ligation of mIgM or mIgD results in rapid activation of a phospholipase C and a tyrosine kinase(s), these receptors have cytoplasmic tails of only three amino acid residues (Lys-Val-Lys), which seem ill suited for direct physical coupling with cytoplasmic signal transduction structures. In this report, we identify the alpha, beta, and gamma-components of the mIgM-associated phosphoprotein complex, which may play a role in signal transduction. Proteolytic peptide mapping demonstrated that the IgM-alpha chain differs from Ig-beta and Ig-gamma. The chains were purified, and amino-terminal sequencing revealed identity with two previously cloned B-cell-specific genes. One component, IgM-alpha, is a product of the mb-1 gene, and the two additional components, Ig-beta and Ig-gamma, are products of the B29 gene. Immunoblotting analysis using rabbit antibodies prepared against predicted peptide sequences of each gene product confirmed the identification of these mIgM-associated proteins. The deduced sequence indicates that these receptor subunits lack inherent protein kinase domains but include common tyrosine-containing sequence motifs, which are likely sites of induced tyrosine phosphorylation.