Mutational analysis identifies a conserved serine residue important for HAE protein kinase function. A: Alignment of activation segment of 3 Arabidopsis RLKs. Blue box contains BRI1-T1049, BAK1-T455, and HAE-S861. B: Total protein and phosphoprotein stains of gel containing MBP-HAE, MBP-HAE-K711E, and MBP-HAE-S861A. C: Average wildtype-normalized signal for MBP-HAE, MBP-HAE-K711E, and MBP-HAE-S861A across three sets of biological replicates run on a single gel. * indicates significance at p-value < .01, Student's t-test. Error bars represent standard deviation of 3 biological replicates.