Tandem kappa immunoglobulin promoters are equally active in the presence of the kappa enhancer: implications for models of enhancer function.

Transcription of immunoglobulin kappa genes is regulated by enhancer and promoter elements, both of which function in a tissue-specific fashion. We have studied the interaction of these elements by transfecting plasmacytoma cells with genes that have tandem kappa promoters located next to a single kappa enhancer and assaying these genes for transient or stable transcription. We find that the promoters located proximal and distal to the enhancer function identically whether they are separated by 440 bp or by 2.7 kb or whether they are located 1.7 or 7.7 kb away from the enhancer. Our results indicate that the immunoglobulin kappa enhancer does not operate as a bidirectional entry site for RNA polymerase or for other factors associated with the transcription complex. Rather, they suggest that the enhancer exerts its influence uniformly over large distances and independently of the presence of intervening promoters.