Mutations of Ser-23 of the α1 subunit of the rat Na+/K+-ATPase to negatively charged amino acid residues mimic the functional effect of PKC-mediated phosphorylation
| Autor: | Larisa A. Vasilets, Rolf Postina, Svetlana N. Kirichenko |
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| Rok vydání: | 1999 |
| Předmět: |
Mutant
Biophysics Xenopus Biology Biochemistry Ouabain Xenopus laevis Structural Biology Serine Genetics medicine Animals Mimicry PKC Phosphorylation Na+/K+-ATPase Molecular Biology Protein Kinase C Protein kinase C DNA Primers Base Sequence Molecular Mimicry Cell Biology biology.organism_classification Rats Mutagenesis Site-Directed Potassium Posttranslational modification Target protein Sodium-Potassium-Exchanging ATPase Function (biology) Regulation medicine.drug |
| Zdroj: | FEBS Letters. 455:8-12 |
| ISSN: | 0014-5793 |
| DOI: | 10.1016/s0014-5793(99)00851-0 |
| Popis: | The Na+/K+-ATPase is a target protein for protein kinase C (PKC). The PKC-mediated phosphorylation of the rat alpha1 subunit at Ser-23 results in the inhibition of its transport function. To understand the molecular basis of the inhibition by PKC, the Ser-23 in the rat alpha1 subunit has been replaced by negatively (Asp, Glu) or positively (Lys) charged, or uncharged (Gln, Ala) residues, and the mutants were expressed in Xenopus oocytes. Ouabain-specific 86Rb uptake and pump-generated current as well as sensitivity to ouabain and to external K+ have been investigated. When Ser-23 was replaced by the negatively charged residues, transport function was inhibited, and simultaneously synthesis of the alpha subunits was enhanced. In addition, if Ser-23 was substituted by Glu, the K(I) value for inhibition of transport by ouabain was drastically increased from 46.5 microM to 1.05 mM. The data suggest that insertion of a negative charge within the N-terminus of alpha subunit of the Na+/K+-ATPase due to phosphorylation of Ser-23 plays an important role in the PKC-mediated inhibition of transport function. |
| Databáze: | OpenAIRE |
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