Pyruvate transport
Efflux of the end-product of glycolysis, pyruvate, is also mediated by a facilitated diffusion carrier (Barnard et al., 1993, Wiemer et al., 1992, 1995b). The transporter is saturable (Km pyruvate = 2 mM) and exhibits the phenomenon of transacceleration, typical of facilitated diffusion carriers. This carrier differs from monocarboxylate transporters for pyruvate and lactate of mammals, on the basis of its sensitivity for inhibitors. It is inhibited by monocarboxylic acids, but not by lactate. Moreover, inhibition of the transporter by a specific inhibitor such as the alpha-cyanocinnamate derivative UK5099 led to a dramatic accumulation of pyruvate inside the cell and an acidification of the cytosol, suggesting that pyruvate is co-transported with H+ (Wiemer et al., 1995b). Under these conditions respiration and glycolysis stop and the cells lyse.