Functional compartmentation of carbohydrate metabolism

Research efforts in our laboratory have been directed towards elucidation of the relations between metabolism and function in vascular smooth muscle (VSM). During the course of these studies, we have observed that cytosolic carbohydrate metabolism is functionally compartmented. That is, while glycogenolysis and oxidative metabolism are strongly correlated with isometric force and the underlying actomyosin ATPase, the aerobic production of lactate operates independently, and this glycolysis is related to the activity of membrane ion pumps.¹ Further investigation led us to propose that this functional compartmentation of metabolism reflects a true biochemical compartmentation, with at least two separate Embden-Meyerhof pathways for glycolysis and glycogenolysis.² We would like to propose that this is but one example of a more general pattern of organization in living cells, i.e., enzyme cascades for metabolic-energy transformation are colocalized with specific energy-dependent processes.