Molecular model of histidine phospho-carrier
protein HPR (pdb code: 1poh)(ribbon diagram,
cylinders are alpha-helices, His-15 shown as ball-
and-stick model). HPR is part of the phospho-
enolpyruvate-dependent sugar phospho- transferase
system (PTS), a major carbohydrate active
transport system moving certain hexoses across the
cytoplasmic membrane of bacteria and mycoplasmas.
The His-15 at the active site of HPR accepts a
multi-enzyme system (Enzyme I) and transfers it to
various sugar-specific PTS permeases.