The immunoglobulin octanucleotide: independent activity and selective interaction with enhancers

The thymidine kinase (tk) promoter of herpes simplex virus includes an octanucleotide sequence motif (ATTTGCAT) that is also an essential component of immunoglobulin kappa gene promoters. In the absence of an enhancer, tk promoter derivatives that contain this element support a higher rate of transcription than those that lack it. The action of the kappa enhancer augments that of the octanucleotide in B lymphoid cells; when both elements are present, tk promoter activity is increased by more than an order of magnitude. In contrast, the presence of the octanucleotide in this promoter markedly reduces its response to a nonimmunoglobulin enhancer. These results suggest that the octanucleotide may mediate a selective interaction among promoters and enhancers.