Inhibition of anion transport across the red cell membrane by dinitrophenylation of a specific lysine residue at the H₂DIDS binding site of the band 3 protein

The inhibition of anion transport by dinitrophenylation of the red cell membrane is brought about by the modification of a single lysine residue located on the 17-kDa segment of the band 3 protein. This residue is identical with Lys a, which is also capable of reacting with one of the two isothiocyanate groups of 4,4'-diisothiocyano dihydro-stilbene-2,2'-disulfonate (H2DIDS). The rate of reaction between Lys a and 1-fluoro-2,4-dinitrobenzene is reduced when a second lysine residue on the 35-kDa segment of the band 3 protein becomes dinitrophenylated. This latter residue is not identical with Lys b which is known to be present on the 35-kDa segment and involved in the cross-linking of this segment with the 17-kDa segment by H2DIDS