Four structurally distinct, non-DNA-binding subunits of human nuclear respiratory factor 2 share a conserved transcriptional activation domain

Sajiv Gugneja, Joseph V. Virbasius, Richard C. Scarpulla*

*Corresponding author for this work

Research output: Contribution to journalArticle

96 Scopus citations

Abstract

Nuclear respiratory factor 2 (NRF-2) was previously purified to near homogeneity from HeLa cells on the basis of its ability to bind tandem recognition sites in the rat cytochrome oxidase subunit IV (RCO4) promoter. It consisted of five subunits, α, β1, β2, γ1, and γ2. Sequencing of tryptic peptides from α and from mixtures of the two β or two γ subunits revealed sequence identities with subunits of the mouse GA-binding protein (GABP), a ubiquitously expressed ETS domain activator composed of three subunits, α, β1, and β2. To understand the precise relationship between NRF-2 and GABP, cDNAs for all five NRF-2 subunits have now been cloned and their products have been overexpressed. The results establish that the two additional NRF-2 subunits are molecular variants that differ from GABP β1 and β2 by having a 12-amino-acid insertion containing two serine doublets. PCR and RNase protection assays show that mRNAs for these variants are expressed in the human but not the rodent cells and tissues examined. The insertion did not alter the ability of the β and γ subunits to associate with α, the DNA-binding subunit, nor did it affect the ability of NRF-2 β1 or β2 to direct high-affinity binding of α to tandem sites in the RCO4 promoter. In addition, the four NRF-2 β and γ subunits were equally proficient in activating transcription in transfected cells when fused to a GAL4 DNA-binding domain. The domain responsible for this transcriptional activation was localized by deletion mapping to a region of approximately 70 amino acids that is conserved in all four NRF-2 β and γ subunits. The repeated glutamine-containing hydrophobic clusters within this region bear a strong resemblance to those recently implicated in protein-protein interactions within the transcriptional apparatus.

Original languageEnglish (US)
Pages (from-to)102-111
Number of pages10
JournalMolecular and cellular biology
Volume15
Issue number1
DOIs
StatePublished - Jan 1995

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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