GO:0018423:   protein C-terminal leucine carboxyl O-methyltransferase activity
Catalysis of the reaction: S-adenosyl-L-methionine + protein L-leucine = S-adenosyl-L-homocysteine + protein L-leucine methyl ester. This modification occurs only at the oxygen atoms of the free alpha carboxyl group of a leucine residue at the C-terminus of the protein.