Several proteins that catalyze phosphoryl transfer reactions involving phosphohistidine residues have recently been structurally characterized. The architecture of two histidine kinases defines a new protein kinase fold. The diverse folds of several phosphotransfer proteins appear to be designed to foster protein-protein interactions between transfer partners.
Robinson, V. L., & Stock, A. M. (1999). High energy exchange: Proteins that make or break phosphoramidate bonds. Structure. Current Biology Ltd. https://doi.org/10.1016/S0969-2126(99)80032-X