Proceedings of the National Academy of Sciences · 2005 · 105 citations · 21 references
Life SciencesImmunologyMolecular BiologyInnate ImmunityInsect ImmunologySignal TransductionAdaptor ProteinsImmune Signaling PathwaysInnate Immune ReceptorsInnate Immune RecognitionInnate Immune Signaling PathwaysPattern Recognition ReceptorsLigand-induced DimerizationLigand-induced OligomerizationPeptidoglycan Recognition ProteinsToll-like Receptor Dimerization
Drosophila knockout mutants have placed peptidoglycan recognition proteins (PGRPs) in the two major pathways controlling immune gene expression. We now examine PGRP affinities for peptidoglycan. PGRP-SA and PGRP-LCx are bona fide pattern recognition receptors, and PGRP-SA, the peptidoglycan receptor of the Toll/Dif pathway, has selective affinity for different peptidoglycans. PGRP-LCx, the default peptidoglycan receptor of the Imd/Relish pathway, has strong affinity for all polymeric peptidoglycans tested and for monomeric peptidoglycan. PGRP-LCa does not have affinity for polymeric or monomeric peptidoglycan. Instead, PGRP-LCa can form heterodimers with LCx when the latter is bound to monomeric peptidoglycan. Hence, PGRP-LCa can be said to function as an adaptor, thus adding a new function to a member of the PGRP family.
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