Histidine carrier proteins, ribbon diagrams

Molecular models of the histidine carrier proteins PDB code 1pch, 1poh and 1ptf. Ribbon diagram with 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.