Exhibits phosphohistidine phosphatase activity. H2O + N(pros)-phospho-L-histidyl-[protein] = L-histidyl-[protein] + phosphate H2O + N(tele)-phospho-L-histidyl-[protein] = L-histidyl-[protein] + phosphate Monomer. Expressed abundantly in heart and skeletal muscle. Belongs to the janus family.