Plant pattern recognition receptor complexes at the plasma membrane

► Plant PRRs are surface-localized RLKs or RLPs that form multi-protein complexes. ► The LRR-RLK BAK1 is a major regulator of several PRR-mediated pathways. ► The LysM-RLK CERK1 is part of multi-specificity recognition complexes. ► The cytoplasmic kinase BIK1 is a key regulator of PTI downstream of multiple PRRs. ► Phosphorylation and ubiquitination events regulate the activity of PRR complexes. A key feature of innate immunity is the ability to recognize and respond to potential pathogens in a highly sensitive and specific manner. In plants, the activation of pattern recognition receptors (PRRs) by pathogen-associated molecular patterns (PAMPs) elicits a defense programme known as PAMP-triggered immunity (PTI). Although only a handful of PAMP-PRR pairs have been defined, all known PRRs are modular transmembrane proteins containing ligand-binding ectodomains. It is becoming clear that PRRs do not act alone but rather function as part of multi-protein complexes at the plasma membrane. Recent studies describing the molecular interactions and protein modifications that occur between PRRs and their regulatory proteins have provided important mechanistic insight into how plants avoid infection and achieve immunity.