Steroid hormones exert their principal genomic effects by binding to nuclear receptors that act as ligand-activated transcription factors. Which structural domain of the nuclear receptor directly contacts the hormone response element (HRE) on DNA?

• A DNA-binding domain (DBD) containing zinc finger motifs ✓
• B Ligand-binding domain (LBD) at the C-terminus
• C N-terminal activation function-1 (AF-1) domain
• D Hinge region providing flexible dimerisation

Explanation

The DNA-binding domain (DBD), located centrally in the nuclear receptor protein, contains two Cys2-Cys2 zinc finger motifs that fold around zinc ions and make direct base-specific contacts with the HRE palindromic sequence. The LBD binds the hormone and harbours AF-2 for coactivator recruitment. The N-terminal AF-1 domain has ligand-independent transactivation function. The hinge region provides flexibility for dimerisation but does not contact DNA directly.

Reference: Harper's Illustrated Biochemistry, 32nd ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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