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Updated: Aug 7, 2026

Reverse Yeast Two-hybrid System to Identify Mammalian Nuclear Receptor Residues that Interact with Ligands and/or Antagonists
Published on: November 16, 2013
Ligand specificity and ligand-induced conformational change in gal repressor
Sumana Chatterjee1, Kajari Ghosh, Amlanjyoti Dhar
1Department of Biophysics, Bose Institute, P-1/12 C.I.T. Scheme VII M, Calcutta, India.
Abstract:
Gal repressor (GalR) binds D-galactose, which is responsible for lifting of repression of the gal operon. Proton T1 measurements of alpha- and beta-anomers of galactose as a function of gal repressor show preferential binding of the beta-anomer. The beta-anomer was isolated by high-performance liquid chromatography and was shown to bind tightly to GalR. Calorimetry was used to determine enthalpy changes at several temperatures. Heat capacity change was found to be positive, indicating that a significant amount of hydrophobic surface area was exposed upon galactose binding. Bis-ANS binding to GalR is significantly enhanced in the presence of a saturating amount of galactose, indicating additional exposure of hydrophobic surfaces. We propose that the galactose-induced conformational change involves the opening of the two subdomains, which may disrupt protein-protein interactions responsible for repression.
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