This old version of Proteopedia is provided for student assignments while the new version is undergoing repairs. Content and edits done in this old version of Proteopedia after March 1, 2026 will eventually be lost when it is retired in about June of 2026.
Apply for new accounts at the new Proteopedia. Your logins will work in both the old and new versions.
1by4
From Proteopedia
STRUCTURE AND MECHANISM OF THE HOMODIMERIC ASSEMBLY OF THE RXR ON DNA
Overview
The 9-cis retinoic acid receptor, RXR, binds DNA effectively as a homodimer or as a heterodimer with other nuclear receptors. The DNA-binding sites for these RXR complexes are direct repeats of a consensus sequence separated by one to five base-pairs of intervening space. Here, we report the 2.1 A crystal structure of the RXR-DNA-binding domain as a homodimer in complex with its idealized direct repeat DNA target. The structure shows how a gene-regulatory site can induce conformational changes in a transcription factor that promote homo-cooperative assembly. Specifically, an alpha-helix in the T-box is disrupted to allow efficient DNA-binding and subunit dimerization. RXR displays a relaxed mode of sequence recognition, interacting with only three base-pairs in each hexameric half-site. The structure illustrates how site selection is achieved in this large eukaryotic transcription factor family through discrete protein-protein interactions and the use of tandem DNA binding sites with characteristic spacings.
About this Structure
1BY4 is a Single protein structure of sequence from Homo sapiens. Full crystallographic information is available from OCA.
Reference
Structural basis of RXR-DNA interactions., Zhao Q, Chasse SA, Devarakonda S, Sierk ML, Ahvazi B, Rastinejad F, J Mol Biol. 2000 Feb 18;296(2):509-20. PMID:10669605 Page seeded by OCA on Fri May 2 12:06:18 2008
