Arginyl residues are involved in the transport of Fe2+ through the plasma membrane of the mammalian reticulocyte.
Sealed reticulocyte ghosts were treated with reagents that modify a variety of amino acid residues. Only ninhydrin and phenylglyoxal, both modifiers of arginyl residues, produced inhibition of the initial rate of 59Fe2+ uptake. The inhibition (i) was dependent on the concentration of ninhydrin or phenylglyoxal, (ii) increased from pH 7 to 9, a feature of the modification of arginine by ninhydrin or phenylglyoxal, and (iii) was blocked when Fe2+ was present during the modification step. A23187, an effective membrane Fe2+ transporter, diminished the inhibitory effect of ninhydrin and phenylglyoxal, indicative that the transport of iron through the membrane, and not a secondary process, was selectively inhibited. We conclude that the iron transporter from the plasma membrane of erythroid cells has one or more arginyl residues in a segment accessible to ninhydrin or phenylglyoxal, and that this residue is involved in the transmembrane transport of iron.
González-Sepúlveda
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Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Santiago.
Núñez
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D000818:Animals; D001120:Arginine; D001692:Biological Transport / Q000187:drug effects; D000001:Calcimycin / Q000494:pharmacology; D004910:Erythrocyte Membrane / Q000187:drug effects / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007501:Iron / Q000097:blood*; D007504:Iron Radioisotopes; D007700:Kinetics; D008322:Mammals; D009555:Ninhydrin / Q000494:pharmacology; D010658:Phenylglyoxal / Q000494:pharmacology; D012156:Reticulocytes / Q000378:metabolism*; D014634:Valinomycin / Q000494:pharmacology
D007504:Iron Radioisotopes; D014634:Valinomycin; D000001:Calcimycin; D001120:Arginine; D007501:Iron; D009555:Ninhydrin; D010658:Phenylglyoxal