Glutamine-Binding　Protein　(GlnBP)　of　Escherichia　coli,　an　important　member　of　the　periplasmic　binding　protein　family,　is　responsible　for　the　first　step　in　the　active　transport　of　glutamine　across　the　cytoplasmic　membrane.　In　this　work,　the　functionally　key　regulation　sites　of　GlnBP　were　identified　by　utilizing　a　perturbation　method　proposed　by　our　group,　in　which　the　residues　whose　perturbations　markedly　change　the　binding　free　energy　between　GlnBP　and　glutamine　are　considered　to　be　functionally　key　residues.　The　results　show　that　besides　the　substrate　binding　sites,　some　other　residues　distant　from　the　binding　pocket,　including　the　ones　in　the　hinge　regions　between　the　two　domains,　the　front-and　backdoor　channels　and　the　exposed　region,　are　important　for　the　function　of　glutamine　binding　and　transport.　The　predicted　results　are　well　consistent　with　the　theoretical　and　experimental　data,　which　indicates　that　our　method　is　an　effective　approach　to　identify　the　key　residues　important　for　both　ligand　binding　and　long-range　allosteric　signal　transmission.　This　work　can　provide　some　insights　into　the　function　performance　of　GInBP　and　the　physical　mechanism　of　its　allosteric　regulation.　(C)　2016　Elsevier　Ltd.　All　rights　reserved.