In enzymology, a 6-methylsalicylic-acid synthase () is a polyketide synthase that catalyzes the chemical reaction acetyl-CoA + 3 malonyl-CoA + NADPH + H+ 6-methylsalicylate + 4 CoA + 3 CO2 + NADP+ + H2O The 4 substrates of this enzyme are acetyl-CoA, malonyl-CoA, NADPH, and H+, whereas its 5 products are 6-methylsalicylate, CoA, CO2, NADP+, and H2O. This enzyme belongs to the family of transferases, specifically those acyltransferases transferring groups other than aminoacyl groups. The systematic name of this enzyme class is acyl-CoA:malonyl-CoA C-acyltransferase (decarboxylating, oxoacyl-reducing, thioester-hydrolysing and cyclizing). Other names in common use include MSAS, and 6-methylsalicylic acid synthase. References EC 2.3.1 NADPH-dependent enzymes Enzymes of unknown structure