AtPep1 is an endogenous peptide elicitor from Arabidopsis leaves that signals the activation of components of the innate immune response against pathogens. Atpep1 derives from the carboxyl terminal of the precursor propeptide PROPEP1, and on microbe-associated molecular pattern (MAMP) perception or cell damage, vacuolar membrane-resident PROPEP1 is processed by type II metacaspases to release AtPep1 which binds to the leucine-rich repeat receptor kinase (LLR-RK) PEPR1. AtPep1 binding to PEPR1 leads to heterodimerization with the shared receptor kinase Brassinosteroid-Insensitive 1-Associated Receptor Kinase 1 (BAK1) and consequent activation of the receptor complex, resulting in immune responses similar to those induced by pathogens.
