Beta subunit of fatty acid synthetase (FAS); the FAS complex catalyzes the synthesis of long-chain saturated fatty acids and is subject to allosteric regulation by palmitoyl-CoA binding distal to the catalytic site to inhibit ketoacyl reductase activity; contains acetyltransacylase, dehydratase, enoyl reductase, malonyl transacylase, and palmitoyl transacylase activities; specific target of the broad-spectrum antifungal NPD6433