This family contains a diverse range of structurally related DNA repair proteins. The superfamily is called the HhH-GPD family after its hallmark Helix-hairpin-helix and Gly/Pro rich loop followed by a conserved aspartate [2]. This includes endonuclease III, EC:4.2.99.18 and MutY an A/G-specific adenine glycosylase, both have a C terminal 4Fe-4S cluster. The family also includes 8-oxoguanine DNA glycosylases such as Swiss:P53397. The methyl-CPG binding protein MBD4 Swiss:Q9Z2D7 also contains a related domain [1] that is a thymine DNA glycosylase. The family also includes DNA-3-methyladenine glycosylase II EC:3.2.2.21 and other members of the AlkA family.

1: The thymine glycosylase MBD4 can bind to the product of deamination at methylated CpG sites. Hendrich B, Hardeland U, Ng HH, Jiricny J, Bird A; Nature 1999;401:301-304. PMID:10499592

2: Structural basis for recognition and repair of the endogenous mutagen 8-oxoguanine in DNA. Bruner SD, Norman DP, Verdine GL; Nature 2000;403:859-866. PMID:10706276