A motif (HIT) related to the sequence H-ϕ-H-ϕ-H-ϕ-ϕ (where ϕ is a hydrophobic amino acid). Proteins containing HIT domains form a superfamily with nucleotide-binding and diadenosine polyphosphate hydrolase activities. Examples include aprataxin, and the GalT subfamily of nucleoside monophosphate transferases (e.g. galactose-1-phosphate uridylyltransferase) that bind zinc and iron. The fragile histidine triad (FHIT) gene encodes a protein (fragile histidine triad protein,147 aa) that has AP3A hydrolase (dinucleoside-triphosphatase, EC 126.96.36.199) activity and may be a tumour suppressor. Histidine triad nucleotide-binding protein 5 (337 aa) is an mRNA decapping enzyme.
Subjects: Medicine and Health.