Radiation Inactivation Suggests That Human Multidrug Resistance-Associated Protein 1 Occurs as a Dimer in the Human Erythrocyte Membrane

• Published in: Archives of biochemistry and biophysics 1998-06, Vol.354 (2), p.311-316
• Main Authors: Soszyński, Mirosław, Kałużna, Agnieszka, Rychlik, Błażej, Sokal, Adam, Bartosz, Grzegorz
• Format: Article
• Language: English
• Subjects: 2,4-Dinitrophenol - metabolism; Adenosine Triphosphatases - metabolism; Adult; ATP-Binding Cassette Transporters - chemistry; ATP-Binding Cassette Transporters - metabolism; Biological Transport - radiation effects; Dimerization; erythrocyte; Erythrocyte Membrane - chemistry; Erythrocyte Membrane - metabolism; Erythrocyte Membrane - radiation effects; Glutathione - analogs & derivatives; Glutathione - metabolism; glutathioneS-conjugates; Humans; In Vitro Techniques; membrane; multidrug resistance-associated protein; Multidrug Resistance-Associated Proteins; radiation inactivation
• ISSN: 0003-9861; 1096-0384
• DOI: 10.1006/abbi.1998.0687

Molecular masses of functional units of two components of 2,4-dinitrophenyl-S-glutathione (DNP-SG) transport across the erythrocyte membrane determined by radiation inactivation were 437 ± 69 kDa for the high-affinity component and 466 ± 67 kDa for the low-affinity component. These results confirm that the multidrug resistance-associated protein (MRP) 1 is responsible for the high-affinity DNP-SG transport across the erythrocyte membrane and suggest that MRP1 exists in the membrane as a dimer. The molecular size of the low-affinity transporter is similar if not identical to that of MRP1. Moreover, while the molecular mass of the DNP-SG-ATPase activity of the erythrocyte membrane corresponds also to that of MRP (375 ± 36 kDa), the molecular mass of the functional unit of dinitrophenol-stimulated ATPase is significantly lower (232 ± 26 kDa), which suggests that thisactivity is linked to a different protein, perhapsaminophospholipid translocase.