Functional role of arginine 375 in transmembrane helix 6 of multidrug resistance protein 4 (MRP4/ABCC4)
Autor: | Frans G. M. Russel, Azza A.K. El-Sheikh, Jan B. Koenderink, Jeroen J. M. W. van den Heuvel, Elmar Krieger |
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Rok vydání: | 2008 |
Předmět: |
Models
Molecular DNA Complementary Arginine Guanosine Monophosphate Membrane transport and intracellular motility [NCMLS 5] Synthetic Organic Chemistry Biology Kidney Protein Structure Secondary Cell Line Cell membrane Serine Metabolism transport and motion [NCMLS 2] Protein structure medicine Humans Fluorescent Antibody Technique Indirect Renal disorder [IGMD 9] Pharmacology chemistry.chemical_classification Alanine Binding Sites Dose-Response Relationship Drug Multidrug resistance-associated protein 2 Cell Membrane Poverty-related infectious diseases [N4i 3] Biological Transport Molecular biology Cellular Structures Protein Structure Tertiary Amino acid Pathogenesis and modulation of inflammation [N4i 1] Renal disorders [UMCN 5.4] Kinetics Transmembrane domain Methotrexate medicine.anatomical_structure Amino Acid Substitution Biochemistry chemistry Growth and differentiation [NCMLS 3] CGMP transport Molecular Medicine Multidrug Resistance-Associated Proteins Baculoviridae Protein Binding |
Zdroj: | Molecular Pharmacology, 74, 4, pp. 964-971 Molecular Pharmacology, 74, 964-971 |
ISSN: | 0026-895X |
Popis: | Contains fulltext : 70256.pdf (Publisher’s version ) (Open Access) Multidrug resistance protein (MRP) 4 transports a variety of endogenous and xenobiotic organic anions. MRP4 is widely expressed in the body and specifically localized to the renal apical proximal tubule cell membrane, where it mediates the excretion of these compounds into urine. To characterize the MRP4 substrate-binding site, the amino acids Phe368, Phe369, Glu374, Arg375, and Glu378 of transmembrane helix 6, and Arg998 of helix 12, localized in the intracellular half of the central pore, were mutated into the corresponding amino acids of MRP1 and MRP2. Membrane vesicles isolated from human embryonic kidney 293 cells overexpressing these mutants showed significantly reduced methotrexate (MTX) and cGMP transport activity compared with vesicles that expressed wild-type MRP4. The only exception was substitution of Arg375 with serine, which had no effect on cGMP transport but significantly decreased the affinity of MTX. Substitution of the same amino acid with a positively charged lysine returned the MTX affinity to that of the wild type. Furthermore, MTX inhibition of MRP4-mediated cGMP transport was noncompetitive, and the inhibition constant was increased by introduction of the R375S mutation. A homology model of MRP4 showed that Arg375 and Arg998 face right into the central aqueous pore of MRP4. We conclude that positively charged amino acids in transmembrane helices 6 and 12 contribute to the MRP4 substrate-binding pocket. 8 p. |
Databáze: | OpenAIRE |
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