title: Labeling of human erythrocyte band 3 with maltosylisothiocyanate. Interaction with the anion transporter.
abstract: Maltosylisothiocyanate (MITC), synthesized as an affinity label for the hexose carrier, has been reported to label a Band 3 or Mr = 100,000 protein in human erythrocytes, in contradistinction to many studies showing the carrier as a Band 4.5 or Mr = 45,000-66,000 protein on gel electrophoresis. In this work the possibility that MITC interacts with the Band 3 anion transporter was studied. In intact human erythrocytes, MITC labeling was largely confined to Band 3 and was decreased by several competitive inhibitors of hexose transport. However, MITC also appeared to react with the anion transport protein, since MITC labeling of Band 3 was irreversibly decreased by the anion transport inhibitor 4,4'-diisothiocyanostilbene-2,2'-disulfonate (DIDS) and since MITC also irreversibly inhibited both tritiated dihydro-DIDS labeling of Band 3 and sulfate uptake in intact cells. Although 20 microM DIDS had little effect on hexose transport, the labeling of erythrocyte Band 3 by the dihydro analog was significantly diminished by competitive inhibitors of hexose transport. These data suggest that MITC labels in part the anion transporter as well as other DIDS-reactive sites on Band 3 which appear to be sensitive to competitive inhibitors of hexose transport.
mesh_terms: D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid / Q000031:analogs & derivatives; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D000345:Affinity Labels; D001457:Anion Exchange Protein 1, Erythrocyte / Q000378:metabolism*; D027321:Anion Transport Proteins; D001667:Binding, Competitive; D002352:Carrier Proteins / Q000037:antagonists & inhibitors / Q000097:blood*; D004910:Erythrocyte Membrane / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism; D006801:Humans; D017879:Isothiocyanates; D008970:Molecular Weight; D009004:Monosaccharide Transport Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D013431:Sulfates / Q000097:blood; D013861:Thiocyanates / Q000097:blood*
chemical_list: D000345:Affinity Labels; D001457:Anion Exchange Protein 1, Erythrocyte; D027321:Anion Transport Proteins; D002352:Carrier Proteins; D017879:Isothiocyanates; D009004:Monosaccharide Transport Proteins; D013431:Sulfates; D013861:Thiocyanates; D012856:4-Acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic Acid; C018564:dihydro-DIDS; C024937:maltosyl isothiocyanate; D017878:4,4'-Diisothiocyanostilbene-2,2'-Disulfonic Acid