Transfer and expression of plasmids containing human cytomegalovirus immediate-early gene 1 promoter-enhancer sequences in eukaryotic and prokaryotic cells.

The human cytomegalovirus immediate-early gene region 1 promoter-enhancer is active in bacteria and in many mammalian cells. Recombinant plasmids containing portions of this DNA can be used to promote the expression of foreign proteins in many cells. In this communication, we report the optimal conditions for transfer of plasmid DNA to cells by electroporation and the transient expression assays which document the activity of different promoter constructions. The observed activity of the human cytomegalovirus promoter is more than 100-fold higher than the activity of the early promoter of SV40.