InterPro domain: IPR038217

MORF4 (mortality factor on chromosome 4), MRG15 (MORF4-related gene on chromosome 15) and MRGX (MORF4-related gene on chromosome X) are members of the MRG protein family that were first identified as transcription factors involved in cellular senescence. All expressed members of the MRG family are localized to the nucleus and have predicted motifs that indicate they function as chromatin remodeling complex components. MORF4, MRG15 and MRGX share a common C-terminal part but a different N-terminal part. The C-terminal similarity of all MRG family members (MORF4, MRG15 and MRGX homologues) defines a new conserved protein domain. The ~170 amino acid MRG domain binds a plethora of transcriptional regulators and chromatin-remodeling factors, including the histone deacetylase transcriptional corepressor mSin3A and the nuclear protein PAM14 (protein-associated MRG, 14kDa) [ 1 , 2 ].

The MRG domain consists of three conserved blocks. It is predominantly hydrophobic, and consists of mainly alpha-helices that are arranged in a three layer sandwich topology. The hydrophobic core is stabilised by interactions among a number of conserved hydrophobic residues. The molecular surface is largely hydrophobic, but contains a few hydrophilic patches [ 3 , 4 , 5 ].

1. Identification of a gene that reverses the immortal phenotype of a subset of cells and is a member of a novel family of transcription factor-like genes. Mol. Cell. Biol. 19, 1479-85
2. Conservation of the MORF4 related gene family: identification of a new chromo domain subfamily and novel protein motif. Gene 266, 111-21
3. Multipurpose MRG domain involved in cell senescence and proliferation exhibits structural homology to a DNA-interacting domain. Structure 14, 151-8
4. The MRG domain of human MRG15 uses a shallow hydrophobic pocket to interact with the N-terminal region of PAM14. Protein Sci. 15, 2423-34
5. Structural basis for molecular interactions involving MRG domains: implications in chromatin biology. Structure 20, 151-60