Identification of critical residues for heterodimerization within the ligand-binding domain of retinoid X receptor.
Nuclear receptors regulate transcription by binding to specific DNA response elements as homodimers or heterodimers with the retinoid X receptors (RXRs). The identity box (I-box), a 40-amino acid region within the ligand-binding domains of RXRs and other nuclear receptors, was recently shown to determine identity in the heterodimeric interactions. Here, we dissected this region in the yeast two-hybrid system by analyzing a series of chimeric receptors between human RXRalpha and rat hepatocyte nuclear factor 4 (HNF4), a distinct member of the nuclear receptor superfamily that prefers homodimerization. We found that the C-terminal 11-amino acid region of the RXR I-box was sufficient to direct chimeric receptors based on the HNF4 ligand-binding domain to heterodimerize with retinoic acid receptors or thyroid hormone receptors. Furthermore, we identified the hRXRalpha amino acids A416 and R421 of the 11-amino acid subregion as most critical determinants of heterodimeric interactions; i.e. mutant HNF4s incorporating only the hRXRalpha A416 or R421 heterodimerized with retinoic acid receptor.
Lee
S K
SK
College of Pharmacy, Chonnam National University, Kwangju, Korea.
Na
S Y
SY
Kim
H J
HJ
Soh
J
J
Choi
H S
HS
Lee
J W
JW
D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D001665:Binding Sites; D004268:DNA-Binding Proteins; D019281:Dimerization; D051557:Hepatocyte Nuclear Factor 4; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D018168:Receptors, Retinoic Acid / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D047488:Retinoid X Receptors; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015003:Yeasts / Q000235:genetics; D000099160:LexA Repressor Protein
D001426:Bacterial Proteins; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D004268:DNA-Binding Proteins; D051557:Hepatocyte Nuclear Factor 4; D010750:Phosphoproteins; D018168:Receptors, Retinoic Acid; D011994:Recombinant Proteins; D047488:Retinoid X Receptors; D012697:Serine Endopeptidases; D014157:Transcription Factors; D000099160:LexA Repressor Protein; C403128:MLX protein, human