Forward transport. 14-3-3 binding overcomes retention in endoplasmic reticulum by dibasic signals.
Proteins with dibasic retention motifs are subject to retrograde transport to endoplasmic reticulum (ER) by COPI-coated vesicles. As forward transport requires escape from ER retention, general release mechanisms have been expected. Here, KCNK3 potassium channels are shown to bear two cytoplasmic trafficking motifs: an N-terminal dibasic site that binds beta-COP ... to hold channels in ER and a C-terminal "release" site that binds the ubiquitous intracellular regulator 14-3-3beta on a nonclassical motif in a phosphorylation-dependent fashion to suppress beta-COP binding and allow forward transport. The strategy appears to be common. The major histocompatibility antigen class II-associated invariant chain Iip35 exhibits dibasic retention, carries a release motif, and shows mutually exclusive binding of beta-COP and 14-3-3beta on adjacent N-terminal sites. Other retained proteins are demonstrated to carry functional 14-3-3beta release motifs.
Mesh Terms:
14-3-3 Proteins, Amino Acid Motifs, Animals, Binding Sites, COS Cells, Cercopithecus aethiops, Coatomer Protein, Endoplasmic Reticulum, Humans, Nerve Tissue Proteins, Peptides, Potassium Channels, Potassium Channels, Tandem Pore Domain, Protein Transport, Rats, Tyrosine 3-Monooxygenase, Valine
14-3-3 Proteins, Amino Acid Motifs, Animals, Binding Sites, COS Cells, Cercopithecus aethiops, Coatomer Protein, Endoplasmic Reticulum, Humans, Nerve Tissue Proteins, Peptides, Potassium Channels, Potassium Channels, Tandem Pore Domain, Protein Transport, Rats, Tyrosine 3-Monooxygenase, Valine
Cell
Date: Nov. 15, 2002
PubMed ID: 12437930
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