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Different cell surface structures have different levels of ezrin phosphorylation
Author(s) -
Zhu Lixin,
Hatakeyama Jason,
Shastri Aditi,
Chen Cheng,
Poon Kevin,
Forte John G
Publication year - 2008
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.22.1_supplement.938.1
Subject(s) - ezrin , microbiology and biotechnology , cytoskeleton , phosphorylation , dephosphorylation , chemistry , cell , radixin , actin , cell membrane , actin cytoskeleton , biophysics , biology , biochemistry , phosphatase
Ezrin, a member of the ERM family, is a membrane‐cytoskeleton linker protein activated by phosphorylation on Thr 567 (T567P). In gastric parietal cells, high turnover of T567P on ezrin is necessary for membrane recycling and acid secretion. Studies using transformed cell lines have reported conflicting results regarding localization and translocation of ezrin with changing T567P levels, challenging the T567P turnover hypothesis. Here we examined this question in several tissues in situ where ezrin plays a pivotal functional role. Surprisingly, T567P levels in kidney and small intestine were >10 times higher than gastric glands. Blocking phosphorylation or dephosphorylation revealed rapid turnover of T567P in all 3 tissues. Immunofluorescence staining showed that decreased T567P did not dislocate ezrin from the respective apical membranes; rather, dephosphorylation of T567P only decreased binding of ezrin to F‐actin, but ezrin‐membrane interaction was unaffected, as indicated by the triton and digitonin extraction analyses. Thus, steady state T567P levels markedly differ at different cell surface structures, but they all show turnover activity consistent with the membrane‐cytoskeleton linker role of ERMs. The data are consistent with an hypothesis that surface plasticity depends on turnover of ERM bonding interactions to take up and relax tension between the plasma membrane and cytoskeleton.