Two-electrode voltage-clamp analysis of Na,K-ATPase asparagine 776 mutants
| Autor: | Sven Geibel, Jan Joep H.H.M. De Pont, Eva Grabsch, Thomas Friedrich, Ernst Bamberg, Jan B. Koenderink |
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| Rok vydání: | 2003 |
| Předmět: |
Patch-Clamp Techniques
Stereochemistry Glutamine Xenopus Sodium Mutant chemistry.chemical_element Biology General Biochemistry Genetics and Molecular Biology History and Philosophy of Science Extracellular Animals Asparagine Na+/K+-ATPase Membrane potential Aspartic Acid Alanine General Neuroscience Wild type Depolarization Recombinant Proteins Rats Renal disorders [UMCN 5.4] Kinetics Protein Subunits Amino Acid Substitution chemistry Oocytes Female Sodium-Potassium-Exchanging ATPase |
| Zdroj: | Annals of the New York Academy of Sciences, 986, pp. 150-4 Annals of the New York Academy of Sciences, 986, 150-4 |
| ISSN: | 0077-8923 |
| DOI: | 10.1111/j.1749-6632.2003.tb07152.x |
| Popis: | Item does not contain fulltext Steady-state and pre-steady-state currents of Asn(776) mutants of Na,K-ATPase are presented. The stationary current generated by N776Q strongly depends on the membrane potential, but has a negative slope, opposite to that of the wild-type enzyme. The apparent rate constant of the reaction sequence E(1)P(Na(+)) E(2)P + Na(+) of this mutant is rather independent of the membrane potential and is at resting and depolarizing membrane potential higher than that of the wild-type enzyme. Thus, the voltage-dependent increase of the rate coefficient of the wild type that is associated with extracellular Na(+) rebinding is almost absent in the N776Q mutant. These findings indicate that dislocating the carboxamide group of Asn(776) decreases the affinity of sodium at its extracellular binding site. |
| Databáze: | OpenAIRE |
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