Inhibition of Na+-dependent phosphate transport by group-specific covalent reagents in rat kidney brush border membrane vesicles. Evidence for the involvement of tyrosine and sulfhydryl groups on the interior of the membrane.

摘要: Abstract The effects of tyrosine- and sulfhydryl-specific reagents on the Na + -dependent transport phosphate in brush border membrane vesicles prepared from rat renal cortex were investigated. This study is first to show that tyrosine-specific 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole tetranitromethane inactivate transporter a concentration- time-dependent fashion while impermeant tyrosine reagent, N -acetylimidazole, has no effect uptake. permeant sulfhydryl reagent -ethylmaleimide also caused time concentration-dependent inactivation this process but 7-chloro-4-sulfobenzo-2-oxa-1,3-diazole eosin-5-malemide had little inhibitory both additive, protection by could be achieved preincubation with substrates or competitive inhibitors process. These results suggest amino acids modified these agents are located either within cytosolic surface transporter. residues may not participate substrate binding, important for conformational change necessary translocation across membranes. shows can inactivated other which covalently modify histidine, carboxyl, groups proteins.