A proteomic approach identifies many novel palmitoylated proteins in A rabidopsis

SummaryS ‐acylation (palmitoylation) is a poorly understood post‐translational modification of proteins involving the addition of acyl lipids to cysteine residues. S ‐acylation promotes the association of proteins with membranes and influences protein stability, microdomain partitioning, membrane targeting and activation state. No consensus motif for S ‐acylation exists and it therefore requires empirical identification. Here, we describe a biotin switch isobaric tagging for relative and absolute quantification ( iTRAQ )‐based method to identify S ‐acylated proteins from A rabidopsis. We use these data to predict and confirm S ‐acylation of proteins not in our dataset. We identified c . 600 putative S ‐acylated proteins affecting diverse cellular processes. These included proteins involved in pathogen perception and response, mitogen‐activated protein kinases ( MAPK s), leucine‐rich repeat receptor‐like kinases ( LRR ‐ RLK s) and RLK superfamily members, integral membrane transporters, ATP ases, soluble N ‐ethylmaleimide‐sensitive factor‐activating protein receptors ( SNARE s) and heterotrimeric G ‐proteins. The prediction of S ‐acylation of related proteins was demonstrated by the identification and confirmation of S ‐acylation sites within the SNARE and LRR ‐ RLK families. We showed that S ‐acylation of the LRR ‐ RLK FLS 2 is required for a full response to elicitation by the flagellin derived peptide flg22, but is not required for localization to the plasma membrane. A rabidopsis contains many more S ‐acylated proteins than previously thought. These data can be used to identify S ‐acylation sites in related proteins. We also demonstrated that S ‐acylation is required for full LRR ‐ RLK function.