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Critical role of the Isoform‐Specific Region in Na,K‐ATPase trafficking and Protein Kinase C‐dependent regulation
Author(s) -
Pierre Sandrine V,
Sottejeau Yoann,
Belliard Aude,
Duran MarieJosee,
Pressley Thomas A
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.607.7
Subject(s) - protein kinase c , gene isoform , microbiology and biotechnology , clathrin , mutant , biology , atpase , chemistry , biochemistry , phosphorylation , cell , endocytosis , enzyme , gene
The Isoform Specific Region (ISR) is a region of structural heterogeneity among the 4 isoforms of the Na,K‐ATPase α‐subunit. The ISR participates in PKC regulation of Na,K‐ATPase, a process that involves membrane recycling via clathrin‐coated vesicles. A potential dileucine recognition motif [DE]XXXL[LI] for clathrin adaptors is present in α1 ISR but not in α2. To determine whether a disruption of this motif could explain the change in PKC regulation observed upon ISR exchange, mutants of the rat α1 isoform that replaced the first leucine (L499V) or the glutamate (E495S) of the potential motif were expressed heterologously in opossum kidney cells. In the absence of PKC stimulation, total expression and Na,K‐ATPase mediated 86 Rb + uptake were comparable in the mutants‐ and α1‐expressing cells. However, biotinylation experiments revealed an increase of about 80% in the surface expression upon disruption of the motif, as well as a significant reduction of the basal rate of removal from the cell surface. Upon PKC stimulation, activation of Na,K‐ATPase mediated 86 Rb + uptake was doubled in mutant‐expressing cells, comparable to the chimera containing the intact α2 ISR. This suggests that the ISR plays a critical role in the Na,K‐ATPase isoform‐specific response to PKC activation and in basal Na,K‐ATPase expression at the cell surface.