Methylates the carboxyl group of the C-terminal leucine residue of protein phosphatase 2A (PP2A) catalytic subunits to form alpha-leucine ester residues (Probable) (PubMed:21558554). Involved in brassinosteroid (BR) signaling. Plays a negative role in BR signaling pathway. Functions as a positive regulator of BRI1 receptor-kinase degradation. Methylates PP2A, thus facilitating its association with activated BRI1. This leads to receptor dephosphorylation and degradation, and thus to the termination of BR signaling. May act upstream of ASK7/BIN2 (PubMed:21558554). Involved in methylation of PP2A during environemental stress responses (PubMed:28741704). [phosphatase 2A protein]-C-terminal L-leucine + S-adenosyl-L-methionine = [phosphatase 2A protein]-C-terminal L-leucine methyl ester + S-adenosyl-L-homocysteine Induced by brassinosteroids. Reduced rosette size and early flowering. Reduced length of the main root and reduced number of lateral roots. Belongs to the methyltransferase superfamily. LCMT family. Truncated N-terminus.