This enzyme belongs to the family of transferases, specifically those transferring a phosphate group to the sidechain of histidine residues in proteins (protein-histidine kinases). The systematic name of this enzyme class is ATP:protein-L-histidine Npi-phosphotransferase. Other names in common use include ATP:protein-L-histidine N-pros-phosphotransferase, histidine kinase, histidine protein kinase, protein histidine kinase, protein kinase (histidine), and HK2.
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Huebner VD, Matthews HR (1985). "Phosphorylation of histidine in proteins by a nuclear extract of Physarum polycephalum plasmodia". J. Biol. Chem.260 (30): 16106–13. PMID4066704.