Histidine triad, conserved site
IPR019808
Definition
The Histidine Triad (HIT) motif, His-x-His-x-His-x-x (x, a hydrophobic amino acid) was identified as being highly conserved in a variety of organisms PMID:1472710. Crystal structure of rabbit Hint, purified as an adenosine and AMP-binding protein, showed that proteins in the HIT superfamily are conserved as nucleotide-binding proteins and that Hint homologues, which are found in all forms of life, are structurally related to Fhit homologues and GalT-related enzymes, which have more restricted phylogenetic profiles PMID:9164465. Hint homologues including rabbit Hint and yeast Hnt1 hydrolyse adenosine 5' monophosphoramide substrates such as AMP-NH2 and AMP-lysine to AMP plus the amine product and function as positive regulators of Cdk7/Kin28 in vivo PMID:11805111. Fhit homologues are diadenosine polyphosphate hydrolases PMID:8794732 and function as tumour suppressors in human and mouse PMID:10758156 though the tumour suppressing function of Fhit does not depend on ApppA hydrolysis PMID:9576908. The third branch of the HIT superfamily, which includes GalT homologues, contains a related His-X-His-X-Gln motif and transfers nucleoside monophosphate moieties to phosphorylated second substrates rather than hydrolysing them PMID:12119013. The bovine protein kinase C inhibitor, PKCI-1, is an inhibitor protein that binds zinc without the use of zinc-finger motifs PMID:2307677. Each protein molecule binds one zinc ion via a novel binding site containing 3 closely-spaced histidine residues PMID:1899836. This region, referred to as the histidine triad (HIT) PMID:1899836, has been identified in various prokaryotic and eukaryotic proteins of uncertain function PMID:1472710. The signature pattern used in this entry contains the region of the histidine triad and includes the three conserved histidine residues which are thought to bind the zinc ion.
5 human proteins with this domain
Each is a reviewed human protein in the Seroatlas serome and a potential autoantibody target; this domain groups them into one antibody-relevant category. Every entry links to its own record.
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