Tsao B P, Wang X F, Peterson C L, Calame K
Department of Biological Chemistry, UCLA School of Medicine 90024.
Nucleic Acids Res. 1988 Apr 25;16(8):3239-53. doi: 10.1093/nar/16.8.3239.
We have systematically investigated the functional role of protein binding sites within the mouse immunoglobulin heavy chain enhancer which we previously identified by in vitro binding studies (1,2). Each binding site was deleted, mutant enhancers were cloned 3' of the chloramphenicol acetyl transferase gene in the vector pA10CAT2 and transfected into plasmacytoma cells. We demonstrate that the newly identified site E, located at 324-338 bp, is important for enhancer function; previously identified sites B(uE1), Cl(uE2), C2(uE3) and C3 were also shown to be important for enhancer activity. Sites A and D are not required for IgH enhancer function, as assayed by our methods. Thus, including the octamer site, six protein binding sites which bind at least six different proteins are important for enhancer function in vivo.
我们已经系统地研究了小鼠免疫球蛋白重链增强子内蛋白质结合位点的功能作用，这些位点是我们之前通过体外结合研究鉴定出来的（1,2）。每个结合位点都被删除，将突变的增强子克隆到载体pA10CAT2中氯霉素乙酰转移酶基因的3'端，并转染到浆细胞瘤细胞中。我们证明，新鉴定出的位于324 - 338 bp的位点E对增强子功能很重要；之前鉴定出的位点B（uE1）、C1（uE2）、C2（uE3）和C3也被证明对增强子活性很重要。通过我们的方法检测，位点A和D对于IgH增强子功能不是必需的。因此，包括八聚体位点在内，六个结合至少六种不同蛋白质的蛋白质结合位点对于体内增强子功能很重要。
