Stimulation of transcription from different RNA polymerase II promoters by high mobility group proteins 1 and 2.

High mobility group proteins (HMGs) 1 and 2 are shown to stimulate transcription in vitro from a number of RNA polymerase II promoters. Greatest effects were seen on transcription from the SV40 late promoter, then the SV40 early promoter with similar levels of transcription enhancement being seen for the human metallothionein 2A, adenovirus major late and chicken feather keratin promoters. The results indicate that HMGs 1 and 2 act to increase initiation of transcription in vitro and differential effects on the promoters are consistent with their action being in part to enhance the binding or functional activity of promoter-specific transcription factors.