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Ezrin is a cyclic AMP‐dependent protein kinase anchoring protein
Author(s) -
Dransfield Daniel T.,
Bradford Alvin J.,
Smith Jenetta,
Martin Marianne,
Roy Christian,
Mangeat Paul H.,
Goldenring James R.
Publication year - 1997
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/16.1.35
Subject(s) - biology , ezrin , protein kinase a , anchoring , microbiology and biotechnology , kinase , biochemistry , cytoskeleton , cell , structural engineering , engineering
cAMP‐dependent protein kinase (A‐kinase) anchoring proteins (AKAPs) are responsible for the subcellular sequestration of the type II A‐kinase. Previously, we identified a 78 kDa AKAP which was enriched in gastric parietal cells. We have now purified the 78 kDa AKAP to homogeneity from gastric fundic mucosal supernates using type II A‐kinase regulatory subunit (R II ) affinity chromatography. The purified 78 kDa AKAP was recognized by monoclonal antibodies against ezrin, the canalicular actin‐associated protein. Recombinant ezrin produced in either Sf9 cells or bacteria also bound R II . Recombinant radixin and moesin, ezrin‐related proteins, also bound R II in blot overlay. Analysis of recombinant truncations of ezrin mapped the R II binding site to a region between amino acids 373 and 439. This region contained a 14‐amino‐acid amphipathic α‐helical putative R II binding region. A synthetic peptide containing the amphipathic helical region (ezrin 409–438 ) blocked R II binding to ezrin, but a peptide with a leucine to proline substitution at amino acid 421 failed to inhibit R II binding. In mouse fundic mucosa, R II immunoreactivity redistributed from a predominantly cytosolic location in resting parietal cells, to a canalicular pattern in mucosa from animals stimulated with gastrin. These results demonstrate that ezrin is a major AKAP in gastric parietal cells and may function to tether type II A‐kinase to a region near the secretory canaliculus.