High mobility group proteins 1 and 2 function as general class II transcription factors.
High mobility group (HMG) proteins 1 and 2 are thought to be associated with chromatin enriched in active gene sequences, to stimulate endogenous transcription of class II and III genes using HMG-depleted nuclei, and to bind specific DNA sequences upstream of the coding regions of trout HMG-T and human beta-globin genes. In testing the possibility that these proteins may act as general transcription factors, the run-off transcription of trout protamine, human beta-globin, adenovirus 2 major late promoter, and herpes simplex virus (HSV) thymidine kinase genes was found to be inhibited by affinity-purified HMG-1 and -2 antibodies. The inhibition was partially relieved by exogenously added HMG-1 or -2. A complementation assay showed that the 0.15 M KCl flowthrough of HeLa nuclear extract fractionated by anion-exchange chromatography (DE-52) could be replaced by purified HMG-1 and/or -2 to complement transcription of the trout protamine gene by the 0.5 M KCl eluate fraction. Inhibition studies with heparin showed that HMG-1 and -2 were required for initiation of transcription. These results indicate an absolute requirement of HMG-1 and -2 for class II gene transcription. Western blotting and transcription reconstituted with purified factors show a copurification of HMG-1 and -2 with factor II B, described earlier by Reinberg and Roeder [(1987) J. Biol. Chem. 262, 3310-3321].
Singh
J
J
Department of Medical Biochemistry, Health Sciences Center, University of Calgary, Alberta, Canada.
Dixon
G H
GH
D000818:Animals; D002417:Cattle; D004247:DNA / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D005802:Genes, MHC Class II; D005914:Globins / Q000235:genetics; D006367:HeLa Cells / Q000378:metabolism; D006609:High Mobility Group Proteins / Q000276:immunology / Q000502:physiology*; D011479:Protamines / Q000235:genetics; D014157:Transcription Factors / Q000276:immunology / Q000502:physiology*; D014158:Transcription, Genetic; D014337:Trout; D014764:Viral Proteins / Q000235:genetics
D006609:High Mobility Group Proteins; D011479:Protamines; D014157:Transcription Factors; D014764:Viral Proteins; D005914:Globins; D004247:DNA