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FXYD7, mapping of functional sites involved in endoplasmic reticulum export, association with and regulation of Na,K-ATPase
- Source :
- The Journal of biological chemistry. 279(29)
- Publication Year :
- 2004
-
Abstract
- The brain-specific FXYD7 is a member of the recently defined FXYD family that associates with the alpha1-beta1 Na,K-ATPase isozyme and induces an about 2-fold decrease in its apparent K+ affinity. By using the Xenopus oocyte as an expression system, we have investigated the role of conserved and FXYD7-specific amino acids in the cellular routing of FXYD7 and in its association with and regulation of Na,K-ATPase. In contrast to FXYD2 and FXYD4, the studies on FXYD7 show that the conserved FXYD motif in the extracytoplasmic domain is not involved in the efficient association of FXYD7 with Na,K-ATPase. On the other hand, the conserved Gly40 and Gly29, located on the same face of the transmembrane helix, were found to be implicated both in the association with and the regulation of Na,K-ATPase. Mutational analysis of FXYD7-specific regions revealed the presence of an ER export signal at the end of the cytoplasmic tail. Deletion of a C-terminal valine residue in FXYD7 significantly delayed and decreased its O-glycosylation processing and retarded the rate of its cell surface expression. This result indicates that the C-terminal valine residue is involved in the rapid and selective ER export of FXYD7, which could explain the observed post-translational association of FXYD7 with Na,K-ATPase. In conclusion, our study on FXYD7 provides new information on structural determinants of general importance for FXYD protein action. Moreover, FXYD7 is identified as a new member of proteins with a regulated ER export, which suggests that, among FXYD proteins, FXYD7 has a particular regulatory function in brain.
- Subjects :
- Cytoplasm
DNA, Complementary
Glycosylation
Time Factors
Xenopus
Amino Acid Motifs
DNA Mutational Analysis
Molecular Sequence Data
Glycine
Nerve Tissue Proteins
Endoplasmic Reticulum
Biochemistry
Isozyme
Mice
Xenopus laevis
Valine
Animals
Protein Isoforms
Amino Acid Sequence
Na+/K+-ATPase
Molecular Biology
chemistry.chemical_classification
Binding Sites
Membrane Glycoproteins
biology
Sequence Homology, Amino Acid
Endoplasmic reticulum
Cell Membrane
Brain
Cell Biology
biology.organism_classification
Amino acid
Protein Structure, Tertiary
Electrophysiology
Transmembrane domain
chemistry
Mutation
Oocytes
Sodium-Potassium-Exchanging ATPase
Gene Deletion
Protein Binding
Subjects
Details
- ISSN :
- 00219258
- Volume :
- 279
- Issue :
- 29
- Database :
- OpenAIRE
- Journal :
- The Journal of biological chemistry
- Accession number :
- edsair.doi.dedup.....7ce16e2a6a9130e6389803886b246556