InterPro domain: IPR037446

The histidine phosphatase superfamily is so named because catalysiscentres on a conserved His residue that is transiently phosphorylatedduring the catalytic cycle. Other conserved residues contribute to a'phosphate pocket' and interact with the phospho group of substratebefore, during and after its transfer to the His residue. Structure andsequence analyses show that different families contribute differentadditional residues to the 'phosphate pocket' and, more surprisingly,differ in the position, in sequence and in three dimensions, of acatalytically essential acidic residue. The superfamily may be dividedinto two main branches. The relationship between the two branches isnot evident by (PSI-)BLAST but is clear from more sensitive sequencesearches and structural comparisons [ 1 ].

This entry represents the VIP1 subfamily of the histidine acid phosphatase family. Budding yeast Vip1 is a inositol hexakisphosphate and inositol heptakisphosphate kinase [ 2 ]. The N-terminal domain of yeast Vip1 has inositol-hexakisphosphate kinase activity and is followed by a phosphatase domain of as yet unknown specificity, but which is very likely to act on multiply phosphorylated inositol species [ 3 ].

1. The histidine phosphatase superfamily: structure and function. Biochem. J. 409, 333-48
2. Cloning and characterization of two human VIP1-like inositol hexakisphosphate and diphosphoinositol pentakisphosphate kinases. J. Biol. Chem. 282, 30754-62