Quality control: from molecules to organelles

There is a vast body of literature on the quality control of protein folding and assembly into multisubunit complexes. Such control takes place everywhere in the cell. The correcting mechanisms involve cytosolic and organellar proteases; the result of such control is individual molecules with proper structure and individual complexes both with proper stoichiometry and proper structure. Obviously, the formation of organelles as such requires some additional criteria of correctness and some new mechanisms of their implementation. It is proposed in this article that the ability to carry out an integral (key) function may serve as a criterion of correct organelle assembly and that autophagy can be accepted as a mechanism eliminating the assembly mistakes. (C) 1999 Federation of European Biochemical Societies.