Fig. 4: A conserved tyrosine within the NT part of the ID, predicted to stabilize the ID domain upon ligand binding, is critical for RLP23 (left), RLP42 (middle) and RLP32 (right) function.

a Structural representations of the tripartite complexes of RLP23-nlp20-BAK1, RLP42-pg13-BAK1 and RLP32-IF1-BAK respectively from left to right. pLDDT scores can be found in Supplementary Fig. 2g-i. The ID is highlighted in black, other LRR-RP domains in dark gray. The ligand is depicted in yellow and BAK1 in blue. Residues highlighted in light gray were mutagenized in this study. Besides the conserved Y of interest within the ID, this includes a conserved K within the ID and E within the CT LRR earlier characterized as BAK1 interacting residues for RXEG1. b–d Diverse responses in N. benthamiana post heterologous expression of the respective RLPs and their variants and subsequent treatment with H₂O (white) or 1 μM of the respective ligand (gray). Each biological replicate is represented by at least three technical replicates. Box plots indicate the median and the interquartile range (IQR), the whiskers extend to the most extreme data points within 1.5 times the IQR. Significance was tested by performing non-parametric two-sided Wilcoxon-Mann-Whitney tests between both mock and ligand for each receptor (variant) (depicted in green), as well as the ligand-treated WT receptor vs specific variants, without adjustments for multiple comparisons. The asterisks indicate a significant difference of p < 0.05. b Shown is ROS production (4-60 min) in cumulative RLUs post treatment with H₂O (white) or the respective ligand (1 μM IF1, gray). At least six independent biological replicates (n = 8 (RLP23), or 6 (RLP42 and RLP32) plants) were performed. c Shown are increases in Ca²⁺ cytosolic concentrations (3–30 min), in cumulative RLUs post treatment with H₂O (white) or the corresponding peptides. At least five independent biological replicates (n = 8 (RLP23), or 5 (RLP42), or 7 (RLP32) plants) were performed. d Ethylene accumulation after 4 h treatment. Data points are indicated as gray dots from at least three independent experiments (n = 3 (RLP23, RLP42) or 4 (RLP32) plants). e Proteins extracted from N. benthamiana leaves expressing the respective GFP tagged LRR-RP in combination with Myc-tagged BAK1 and treated with water (–) or 1 µM elicitor (+) for 5 min before collecting were used for co-immunoprecipitation with GFP-trap beads and immunoblotting with tag-specific antibodies. IP, immunoprecipitation PS, Ponceau S. The Pdb files can be found in Supplementary Data 1 and the predicted local distance difference test (pLDDT) scores can be found in Supplementary Fig. 2c, f, i.