Receptor Like Proteins consists of a leucine-rich receptor-like repeat, a transmembrane region of ~25 AA, and a short cytoplasmic region, with no kinase domain. The extracellular leucine rich repeat (eLRR) shows high homology with the RLKs eLRR. RLPs can recognise avirulence genes in a indirect way like Cf2 that recognise the avirulence gene Avr2 through the cysteine protease Rcr3. There are also some hypotheses about a direct recognition, but this has not yet been demonstrated. RLPs lack an obvious signalling domain, suggesting that defence response activation is mediated through interactions with other partner proteins. Activation of RLP typically results in a rapid accumulation of active oxygen species (AOS), changes in cellular ion fluxes, activation of protein kinase cascades, changes in gene expression and, possibly, targeted protein degradation.