third malignant brain tumor (MBT) repeat found in MBT domain-containing protein 1 (MBTD1)
MBTD1 is a putative Polycomb group (PcG) protein that specifically binds to monomethylated and dimethylated 'Lys-20' on histone H4. MBTD1 contains four MBT (malignant brain tumor) repeats. The MBT repeat is a protein module that recognizes methylated lysine residues on histones. MBT repeats contain a semi-aromatic cage to accommodate methyllysine and show specificity towards the lower methylation states of lysine. This model corresponds to the third MBT repeat that does not seem to contain a semi-aromatic cage and may not bind methylated lysine residues.