HIT protein superfamily

Histidine triad (HIT) protein superfamily is an superfamily of nucleotide hydrolases and transferases that binds nucleotides and exert dinucleotidyl hydrolase, nucleotidylyl transferase or phosphoramidate hydrolase enzymatic activity. The HIT superfamily consists of proteins that share the histidine triad motif, His-X-His-X-His-X-X (where X is a hydrophobic amino acid), which constitutes enzymatic catalytic center. HIT proteins are found ubiquitous in all organisms and they are classified into 5 branches, which are represented by human proteins: HINT1, FHIT, Aprataxin, GALT and DCPS. The HINT (Histidine Triad Nucleotide Binding) members and FHIT (Fragile Histidine Triad) have tumor suppressor properties. Aprataxin is implicated in DNA repair mechanisms. DCPS is a scavenger mRNA decapping enzyme. GALT exerts specific nucleoside monophosphate transferase activity^[1][2][3].