Open AccessMonomeric erythrocyte band 3 protein transports anions.
Author(s) -
Sabine Lindenthal,
Dieter Schubert
Publication year - 1991
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.88.15.6540
Subject(s) - band 3 , monomer , vesicle , dimer , chemistry , membrane , phosphatidylcholine , biophysics , covalent bond , size exclusion chromatography , transport protein , crystallography , efflux , membrane protein , chromatography , biochemistry , phospholipid , polymer , biology , organic chemistry , enzyme
The anion transport system of the human erythrocyte membrane was reconstituted in egg phosphatidylcholine membranes by using either the unmodified transport protein, band 3, or covalently crosslinked band 3 dimers. Unilamellar vesicles of a diameter of 32 +/- 3 nm were then isolated from the sample by passage through a French press and subsequent gel filtration. According to sedimentation equilibrium measurements, around 85% of the vesicles were devoid of protein. The remaining 15% contained either a single band 3 monomer or, when crosslinked band 3 protein was used, a single band 3 dimer. Vesicles containing either single monomers or single dimers showed a rapid, inhibitor-sensitive sulfate efflux, and the turnover numbers of band 3 for the inhibitor-sensitive flux component were identical in both systems. This shows that monomeric band 3 protein is able to transport anions and that dimerization of the protein does not change its transport activity.