Staudt L M, Singh H, Sen R, Wirth T, Sharp P A, Baltimore D
Nature. 1986;323(6089):640-3. doi: 10.1038/323640a0.
Immunoglobulin gene promoters are active only in lymphoid cells and this tissue-specific activity requires an octamer sequence, ATTTGCAT. Paradoxically, this same octamer motif seems to be a transcriptional control element in promoters which are active in all tissues. Using an electrophoretic mobility shift assay to identify DNA binding proteins, we have now detected two species of nuclear proteins which bind specifically to this octamer. One previously characterized form (NF-A1) was found in all cell lines tested while the other form (NF-A2) was restricted to lymphoid cell lines. NF-A2 was found in cell lines representing all stages of B-cell differentiation and in half of the T-lymphoma cell lines tested. The identification of a lymphoid-specific octamer binding protein may account for the lymphoid-specific activity of immunoglobulin promoters.
免疫球蛋白基因启动子仅在淋巴细胞中具有活性，这种组织特异性活性需要一个八聚体序列ATTTGCAT。矛盾的是，这个相同的八聚体基序似乎是在所有组织中都具有活性的启动子中的一种转录控制元件。利用电泳迁移率变动分析来鉴定DNA结合蛋白，我们现在已经检测到两种能特异性结合这个八聚体的核蛋白。一种先前已被鉴定的形式（NF-A1）在所有测试的细胞系中都能找到，而另一种形式（NF-A2）则仅限于淋巴细胞系。在代表B细胞分化各个阶段的细胞系以及所测试的一半T淋巴瘤细胞系中都发现了NF-A2。一种淋巴细胞特异性八聚体结合蛋白的鉴定可能解释了免疫球蛋白启动子的淋巴细胞特异性活性。
