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Histidine-containing phosphocarrier protein (HPr)-like proteins. HPr is a central component of the bacterial phosphoenolpyruvate sugar phosphotransferase system (PTS). The PTS catalyses the phosphorylation of sugar substrates during their translocation across the cell membrane. The phosphoryl group from phosphoenolpyruvate is transferred to HPr by enzyme I (EI). Phospho-HPr then transfers the phosphoryl group to one of several sugar-specific phosphoprotein intermediates. The conserved histidine in the N-terminus of HPr serves as an acceptor for the phosphoryl group of EI. In addition to the phosphotransferase proteins HPr and E1, this family also includes the closely related Carbon Catabolite Repressor (CCR) proteins which use the same phosphorylation mechanism and interact with transcriptional regulators to control expression of genes coding for utilization of less favored carbon sources.
Jiyao W et al.(2023). "The conserved domain database in 2023.",