STRUCTURAL INVESTIGATION OF THE ORGANIC A NION TRANSPORT-SYSTEM OF THE RAT-KIDNEY BRUSH-BORDER MEMBRANE BY THE AFFINITY PROBE METHOD

A new method for investigation of the structural organization of the k idney organic anion transport system is suggested, based on the affini ty labeling under conditions of tile transport activation. Organic ani on transporters in the rat kidney bursh border membrane (BBM) were ide ntified using two affinity probes with different reactivity and under two different transport conditions. Bromoacetylated p-amino [H-3]hippu rate was shown to bind covalently under equilibrium exchange condition s to the BBM membrane proteins with molecular masses of 28, 63, 98 and 150 kDa. The data obtained with SITS; and probenecid using as organic anion transport inhibitors indicate that the BBM proteins of 28, 63, and 98 kDa may correspond to the organic anion transport system. The t ransporters were identified under the initial uptake conditions using diazo[3H]hippurate in two versions: by the transport activation with c hloride anions and without activation. Diazo[H-3]hippurate was shown t o bind covalently in the presence of chloride to the BBM proteins with molecular masses of 98 kDa and 28 KDa, whereas in the absence of chlo ride diazohippurate does not bind to anyone protein of this membrane.