The isolation and partial characterization of transferrin binding components of the rabbit reticulocyte plasma membrane.

An affinity chromatograpy method utilising transferrin liganded agarose has been developed for the partial purification of transferrin binding components from Triton X-100 solubilised rabbit reticulocyte plasma membranes. A protein of molecular weight 30-35 000, shown to be located at the reticulocyte extra-cellular surface by lactoperoxidase 125I labelling, was isolated by the affinity method. The protein appeared to form a dimer of molecular weight 65-70 000 in Triton X-100 solution and was shown to associate with both 125I-labelled and unlabelled rabbit transferrin to form a high molecular weight complex in the same solution. N-[14C]Ethylmaleimide appeared to disrupt this association with transferrin and inhibit the formation of the dimer in Triton X-100 by binding to the protein. The protein appeared as a broad band of molecular weight 40 000 on sodium dodecyl sulphate polyacrylamide gel electrophoresis.