Maltosyl isothiocyanate: an affinity label for the glucose transporter of the human erythrocyte membrane. 2. Identification of the transporter.
Maltosyl isothiocyanate (MITC), a potent irreversible inhibitor of glucose transport in human erythrocytes [Mullins, R. E., & Langdon, R. G. (1980) Biochemistry (preceding paper in this issue)], has been found to react almost exclusively with band 3 of the human erythrocyte membrane. The incorporation of [14C]MITC into band 3 was found to be antagonized by transportable sugars or competitive inhibitors of transport. On the basis of [14C]MITC incorporation into band 3 and MITC inhibition of transport, it is estimated that there are 3 x 10(5) glucose transporters present in the erythrocyte membrane. It was found that [14C]MITC-labeled band 3 could be converted into 14C-labeled band 4.5 during the Triton X-100 extraction procedure described by Kasahara & Hinkle [Kasahara, M., & Hinkel, P. C. (1977) J. Biol. Chem. 252, 7384]. On the basis of the evidence presented here and in the preceding paper, it is suggested that in the native erythrocyte membrane a component of band 3 is the glucose transport protein and that during purification with nonionic detergents the transport protein may be enzymatically degraded with some retention of activity.
D000345:Affinity Labels; D001693:Biological Transport, Active; D001786:Blood Glucose / Q000378:metabolism*; D002250:Carbon Radioisotopes; D002352:Carrier Proteins / Q000378:metabolism*; D002918:Chymotrypsin; D004910:Erythrocyte Membrane / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism*; D006801:Humans; D017879:Isothiocyanates; D007700:Kinetics; D008320:Maltose / Q000031:analogs & derivatives*; D008565:Membrane Proteins / Q000302:isolation & purification / Q000378:metabolism*; D009004:Monosaccharide Transport Proteins; D010446:Peptide Fragments / Q000032:analysis; D013861:Thiocyanates
D000345:Affinity Labels; D001786:Blood Glucose; D002250:Carbon Radioisotopes; D002352:Carrier Proteins; D017879:Isothiocyanates; D008565:Membrane Proteins; D009004:Monosaccharide Transport Proteins; D010446:Peptide Fragments; D013861:Thiocyanates; D008320:Maltose; C024937:maltosyl isothiocyanate; D002918:Chymotrypsin