The ligand binding domain of Nurr1 and related nuclear receptor proteins, members of nuclear receptor superfamily
The ligand binding domain of nuclear receptor Nurr1_like: This family of nuclear receptors, including Nurr1, Nerve growth factor-induced-B (NGFI-B) and DHR38 are involved in the embryo development. Nurr1 is a transcription factor that is expressed in the embryonic ventral midbrain and is critical for the development of dopamine (DA) neurons. Structural studies have shown that the ligand binding pocket of Nurr1 is filled by bulky hydrophobic residues, making it unable to bind to ligands. Therefore, it belongs to the class of orphan receptors. However, Nurr1 forms heterodimers with RXR and can promote signaling via its partner, RXR. NGFI-B is an early immediate gene product of embryo development that is rapidly produced in response to a variety of cellular signals including nerve growth factor. It is involved in T-cell-mediated apoptosis, as well as neuronal differentiation and function. NGFI-B regulates transcription by binding to a specific DNA target upstream of its target genes and regulating the rate of tr anscriptional initiation. Another group of receptor in this family is DHR38. DHR38 is the Drosophila homolog to the vertebrate NGFI-B-type orphan receptor. It interacts with the USP component of the ecdysone receptor complex, suggesting that DHR38 might modulate ecdysone-triggered signals in the fly, in addition to the ECR/USP pathway. Nurr1_like proteins exhibit a modular structure that is characteristic for nuclear receptors; they have a central well conserved DNA binding domain (DBD), a variable N-terminal domain, a non-conserved hinge and a C-terminal ligand binding domain (LBD).