preferred_name: holo-[2-methylbutanoate polyketide synthase] + 2 malonyl-CoA + S-adenosyl-L-methionine + 2 NADPH + 3 H(+) => (S)-2-methylbutanoyl-[2-methylbutanoate polyketide synthase] + S-adenosyl-L-homocysteine + 2 CO2 + 2 NADP(+) + 2 CoA + H2O