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Nucleic Acids Res. 1999 Apr 1;27(7):1635-41.

Orientation and positional mapping of the subunits of the multicomponent transcription factors RFX and X2BP to the major histocompatibility complex class II transcriptional enhancer.

Author information

1
Department of Microbiology and Immunology, Emory University School of Medicine, Emory University, Atlanta, GA 30322, USA.

Abstract

Major histocompatibility complex class II genes contain a common complex enhancer that allows for their coordinate regulation. The X box element of the enhancer cooperatively binds the multisubunit transcription factors RFX and X2BP. RFX is an essential class II transcription factor and contains three distinct proteins: RFX5, RFX-B/Ank and RFXAP. X2BP, a CREB/ATF family transcription factor, most likely binds as a homodimer. A site-specific protein-DNA photocrosslinking assay was used to investigate the interactions of the subunits of RFX and X2BP with X box DNA. Two of the RFX subunits, RFX5 and RFX-B/Ank, were found to bind defined sites within the X1 half of the X box. The third RFX subunit, RFXAP, made extensive X1 box contacts. The subunits of X2BP made contacts with the edges of the X2 half of the X box in a manner consistent with other bZIP transcription factor contact patterns. The resulting map provides specific base pair contacts and subunit orientation with respect to the DNA sequence of the RFX-X2BP-X box complex. Our results suggest possible stoichiometry of the RFX subunits and potential interaction between RFX-B/Ank and RFXAP with one of the subunits of X2BP.

PMID:
10075994
PMCID:
PMC148366
DOI:
10.1093/nar/27.7.1635
[Indexed for MEDLINE]
Free PMC Article

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