14-3-3 dimers probe the assembly status of multimeric membrane proteins
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14-3-3 dimers probe the assembly status of multimeric membrane proteins. / Yuan, Hebao; Michelsen, Kai; Schwappach, Blanche.
in: CURR BIOL, Jahrgang 13, Nr. 8, 15.04.2003, S. 638-46.Publikationen: SCORING: Beitrag in Fachzeitschrift/Zeitung › SCORING: Zeitschriftenaufsatz › Forschung › Begutachtung
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TY - JOUR
T1 - 14-3-3 dimers probe the assembly status of multimeric membrane proteins
AU - Yuan, Hebao
AU - Michelsen, Kai
AU - Schwappach, Blanche
PY - 2003/4/15
Y1 - 2003/4/15
N2 - BACKGROUND: Arginine-based endoplasmic reticulum (ER) localization signals are involved in the heteromultimeric assembly of membrane protein complexes like ATP-sensitive potassium channels (K(ATP)) or GABA(B) G protein-coupled receptors. They constitute a trafficking checkpoint that prevents ER exit of unassembled subunits or partially assembled complexes. For K(ATP) channels, the mechanism that leads to masking of the ER localization signals in the fully assembled octameric complex is unknown.RESULTS: By employing a tetrameric affinity construct of the C terminus of the K(ATP) channel alpha subunit, Kir6.2, we found that 14-3-3 isoforms epsilon and zeta specifically recognize the arginine-based ER localization signal present in this cytosolic tail. The interaction was reconstituted by using purified 14-3-3 proteins. Competition with a nonphosphorylated 14-3-3 high-affinity binding peptide implies that the canonical substrate binding groove of 14-3-3 is involved. Comparison of monomeric CD4, dimeric CD8, and artificially tetramerized CD4 fusions correlates the copy number of the tail containing the arginine-based signal with 14-3-3 binding, resulting in the surface expression of the membrane protein. Binding experiments revealed that the COPI vesicle coat can specifically recognize the arginine-based ER localization signal and competes with 14-3-3 for the binding site.CONCLUSIONS: The COPI vesicle coat and proteins of the 14-3-3 family recognize arginine-based ER localization signals on multimeric membrane proteins. The equilibrium between these two competing reactions depends on the valency and spatial arrangement of the signal-containing tails. We propose a mechanism in which 14-3-3 bound to the correctly assembled multimer mediates release of the complex from the ER.
AB - BACKGROUND: Arginine-based endoplasmic reticulum (ER) localization signals are involved in the heteromultimeric assembly of membrane protein complexes like ATP-sensitive potassium channels (K(ATP)) or GABA(B) G protein-coupled receptors. They constitute a trafficking checkpoint that prevents ER exit of unassembled subunits or partially assembled complexes. For K(ATP) channels, the mechanism that leads to masking of the ER localization signals in the fully assembled octameric complex is unknown.RESULTS: By employing a tetrameric affinity construct of the C terminus of the K(ATP) channel alpha subunit, Kir6.2, we found that 14-3-3 isoforms epsilon and zeta specifically recognize the arginine-based ER localization signal present in this cytosolic tail. The interaction was reconstituted by using purified 14-3-3 proteins. Competition with a nonphosphorylated 14-3-3 high-affinity binding peptide implies that the canonical substrate binding groove of 14-3-3 is involved. Comparison of monomeric CD4, dimeric CD8, and artificially tetramerized CD4 fusions correlates the copy number of the tail containing the arginine-based signal with 14-3-3 binding, resulting in the surface expression of the membrane protein. Binding experiments revealed that the COPI vesicle coat can specifically recognize the arginine-based ER localization signal and competes with 14-3-3 for the binding site.CONCLUSIONS: The COPI vesicle coat and proteins of the 14-3-3 family recognize arginine-based ER localization signals on multimeric membrane proteins. The equilibrium between these two competing reactions depends on the valency and spatial arrangement of the signal-containing tails. We propose a mechanism in which 14-3-3 bound to the correctly assembled multimer mediates release of the complex from the ER.
KW - 14-3-3 Proteins
KW - Arginine/metabolism
KW - Binding, Competitive/physiology
KW - Blotting, Western
KW - Endoplasmic Reticulum/physiology
KW - Gene Expression Profiling
KW - HeLa Cells
KW - Humans
KW - Membrane Proteins/metabolism
KW - Potassium Channels, Inwardly Rectifying/metabolism
KW - Precipitin Tests
KW - Signal Transduction/physiology
KW - Tyrosine 3-Monooxygenase/metabolism
U2 - 10.1016/s0960-9822(03)00208-2
DO - 10.1016/s0960-9822(03)00208-2
M3 - SCORING: Journal article
C2 - 12699619
VL - 13
SP - 638
EP - 646
JO - CURR BIOL
JF - CURR BIOL
SN - 0960-9822
IS - 8
ER -