Activation of the TFIID-TFIIA complex with HMG-2.
The nonhistone chromosomal protein HMG-2 was identified as a factor necessary for activation in a defined transcription reaction in vitro containing RNA polymerase II and purified factors. Activation occurred on all promoters assayed except that of the immunoglobulin IgH gene. TFIIA was required for stimulated levels of transcription. The activation process depended on the presence of TAFs in the TFIID complex and generated a preinitiation complex from which TFIIB dissociated more slowly. However, titration of TFIIB over three orders of magnitude did not obviate the requirement of activator and HMG-2 to achieve stimulated levels of transcription. Analysis of the activated reaction identified the TFIID-TFIIA complex as the first stage of modification during activation. These results suggest that activation can occur solely in the presence of the basal factors, activator protein, and an "architectural" HMG factor, which probably stabilizes an activated conformation of the TFIID-TFIIA-promoter complex.
Shykind
B M
BM
Center for Cancer Research, Massachusetts Institute of Technology, Cambridge 02139-4307, USA.
Kim
J
J
Sharp
P A
PA
D001483:Base Sequence; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D006609:High Mobility Group Proteins / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D035561:Transcription Factor TFIIA; D035362:Transcription Factor TFIID; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
D006609:High Mobility Group Proteins; D035561:Transcription Factor TFIIA; D035362:Transcription Factor TFIID; D014157:Transcription Factors