Molecular model (ribbon diagram) of histidine
phosphocarrier protein HPR (PDB code: 1pch),a
component of the phosphoenolpyruvate-dependent
sugar phosphotransferase system (PTS), a major
carbohydrate active-transport system responsible
for transport of certain hexoses across the
cytoplasmic membrane of bacteria and mycoplasmas.
The imidazole group on His-15 (shown as a ball-
and-stick model) at the active site of HPR accepts
a multi-enzyme system (Enzyme I) and transfers it
to various sugar-specific PTS permeases.
