Abstract
Genetic as well as biochemical data suggest that the yeast fatty-acid synthetase complex has an (AB)6 protein structure where A and B represent multifunctional polypeptide chains with molecular weights of 185000 and 180000 daltons, respectively. Subunit A contains at least 3 and subunit B4 of the 8 known biochemical functions of the multienzyme complex. It is concluded that this complex structure has evolved from the corresponding prokaryotic system of monofunctional enzymes due to a selective advantage regarding the biosynthesis and assembly of the complex components.