Molecular compartmentation by enzyme cluster formation. A view over current investigations.

Current investigations in different fields of cellular metabolism focus on the phenomenon of molecular compartmentation as an essential part of metabolic control. This type of compartment without surrounding membranes arises from enzyme cluster formation in the cell. The organization of the enzymes ranges from very loose, non-covalent aggregations, sometimes only transiently associated - dependent on metabolic or developmental state of the cell - to the very fixed, even covalently linked structures. These organized multienzyme systems produce a chemical microheterogeneity concerning the metabolite concentrations in the cell. Molecular compartmentation is the description of this chemical microheterogeneity in a biological term.