Protein 4.1: its association with the human erythrocyte membrane.
125I-labeled protein 4.1a and 4.1b have equal ability to reassociate with inside-out erythrocyte vesicles that were depleted of protein 4.1 in addition to other peripheral membrane proteins. The reassociation of 125I-labeled protein 4.1 to protein 4.1-depleted vesicles at 4 degrees C is salt dependent, pH dependent, and saturable with a Kd of 42-50 nM and an extrapolated maximal binding capacity of 120-140 micrograms of protein 4.1 bound per mg of vesicle protein or 60-70 micrograms of protein 4.1 bound per mg of ghost protein, correlating with the protein 4.1 content in the erythrocyte membrane (6-7% of the total membrane protein). Selective proteolytic cleavage of these vesicles with papain (5 micrograms/ml at 4 degrees C) eliminates greater than 60% of the high-affinity binding sites; therefore, we conclude that the interaction of protein 4.1 with the cytoplasmic membrane surface is through a specific high-affinity protein-protein association.
D001798:Blood Proteins / Q000378:metabolism*; D002918:Chymotrypsin / Q000378:metabolism; D003598:Cytoskeletal Proteins; D004910:Erythrocyte Membrane / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008565:Membrane Proteins / Q000378:metabolism*; D009479:Neuropeptides; D010206:Papain / Q000378:metabolism; D014357:Trypsin / Q000378:metabolism
D001798:Blood Proteins; D003598:Cytoskeletal Proteins; D008565:Membrane Proteins; D009479:Neuropeptides; C028841:erythrocyte membrane band 4.1 protein; C120557:erythrocyte membrane protein band 4.1-like 1; D002918:Chymotrypsin; D014357:Trypsin; D010206:Papain