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Direct association of the unique C-terminal tail of transmembrane AMPA receptor regulatory protein gamma-8 with calcineurin.

Authors: Itakura, M  Watanabe, I  Sugaya, T  Takahashi, M 
Citation: Itakura M, etal., FEBS J. 2014 Mar;281(5):1366-78. doi: 10.1111/febs.12708. Epub 2014 Jan 27.
Pubmed: (View Article at PubMed) PMID:24418105
DOI: Full-text: DOI:10.1111/febs.12708

Transmembrane alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) receptor regulatory proteins (TARPs) are auxiliary subunits that regulate AMPA receptor trafficking to the plasma membrane and localization to postsynaptic sites. The classical TARP family consists of four members: stargazin/gamma-2, gamma-3, gamma-4 and gamma-8. The TARP gamma-8 isoform, which is highly expressed in the hippocampus, has a unique, long C-terminal domain with five distinct regions: two glycine-rich regions, a serine/arginine-rich region, a proline/alanine (P/A) rich region, and a PSD-95/Dlg/ZO-1 (PDZ) binding motif. We performed mass spectrometry and immunoprecipitation assays to identify specific binding partners for the gamma-8 C-terminal tail and found that gamma-8, but not stargazin/gamma-2, co-immunoprecipitated with calcineurin/PP2B, a Ca(2+) /calmodulin-dependent Ser/Thr phosphatase. Co-immunoprecipitation and immunoblot analyses of lysates from COS-7 cells co-transfected with calcineurin and either wild type or chimeric gamma-8 revealed that a section of the C-terminal tail (residues 356-421) can bind calcineurin. Futhermore, gamma-8 lacking the P/A-rich region (residues 383-399) did not bind to calcineurin. In addition, the GST-gamma-8 C-terminal tail (residues 353-414) fusion protein containing the P/A-rich region bound to purified calcineurin in a Ca(2+) /calmodulin-dependent manner, whereas GST-gamma-8 with a deletion of the P/A-rich region did not. Peptide competition assays demonstrated that gamma-8 may interact with the hydrophobic pocket defined by beta-sheet 14 and/or adjacent regions of the catalytic A subunit of calcineurin. These results indicate that the gamma-8 P/A-rich region is essential for binding calcineurin, suggesting that the gamma-8/calcineurin complex may regulate AMPA receptor phosphorylation and trafficking.

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CRRD Object Information
CRRD ID: 8553314
Created: 2014-05-08
Species: All species
Last Modified: 2014-05-08
Status: ACTIVE



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RGD is funded by grant HL64541 from the National Heart, Lung, and Blood Institute on behalf of the NIH.