Asymmetry of the malonate transport system in human red blood cells

Transport kinetics of [2-14C] malonate influx and efflux by the human erythrocyte membrane have been determined as Km(cis), 21mM and Km(trans), 3.2 mM.The flux of this organic dianion is asymmetrically concentration, pH and temperature dependent. Competitive inhibition of malonate by SITS, BPS and sulphate strongly implies that a common route exists for both inorganic anions and organic dianions, namely the anion- exchange band 3 protein. 14C-Malonate which is nonmetabolized in the erythrocyte, is a useful kinetics probe for monitoring membrane potential and self- inhibition.