Abstract
The interaction of the adaptor protein p11, also denoted S100A10, with the C-terminus of the two-pore-domain K+ channel TASK-1 was studied using yeast two-hybrid analysis, glutathione S-transferase pull-down, and co-immunoprecipitation. We found that p11 interacts with a 40 amino-acid region in the proximal C-terminus of the channel. In heterologous expression systems, deletion of the p11-interacting domain enhanced surface expression of TASK-1. Attachment of the p11-interacting domain to the cytosolic tail of the reporter protein CD8 caused retention/retrieval of the construct in the endoplasmic reticulum (ER). Attachment of the last 36 amino acids of p11 to CD8 also caused ER localization, which was abolished by removal or mutation of a putative retention motif (H/K)xKxxx, at the C-terminal end of p11. Imaging of EGFP-tagged TASK-1 channels in COS cells suggested that wild-type TASK-1 was largely retained in the ER. Knockdown of p11 with siRNA enhanced trafficking of TASK-1 to the surface membrane. Our results suggest that binding of p11 to TASK-1 retards the surface expression of the channel, most likely by virtue of a di-lysine retention signal at the C-terminus of p11. Thus, the cytosolic protein p11 may represent a 'retention factor' that causes localization of the channel to the ER.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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14-3-3 Proteins / chemistry
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14-3-3 Proteins / genetics
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14-3-3 Proteins / metabolism
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Amino Acid Sequence
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Animals
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Annexin A2 / chemistry
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Annexin A2 / genetics
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Annexin A2 / metabolism*
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Binding Sites / genetics
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CD8 Antigens / chemistry
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CD8 Antigens / genetics
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CD8 Antigens / metabolism
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CHO Cells
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COS Cells
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Cell Line
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Chlorocebus aethiops
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Cricetinae
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Endoplasmic Reticulum / metabolism*
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Female
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Humans
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In Vitro Techniques
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Models, Biological
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Molecular Sequence Data
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Mutagenesis, Site-Directed
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Nerve Tissue Proteins
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Oocytes / metabolism
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Potassium Channels, Tandem Pore Domain / chemistry
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Potassium Channels, Tandem Pore Domain / genetics
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Potassium Channels, Tandem Pore Domain / metabolism*
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Protein Structure, Tertiary
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RNA Interference
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RNA, Small Interfering / genetics
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Rats
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Recombinant Fusion Proteins / chemistry
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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S100 Proteins / chemistry
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S100 Proteins / genetics
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S100 Proteins / metabolism*
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Sequence Homology, Amino Acid
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Two-Hybrid System Techniques
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Xenopus
Substances
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14-3-3 Proteins
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Annexin A2
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CD8 Antigens
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Nerve Tissue Proteins
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Potassium Channels, Tandem Pore Domain
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RNA, Small Interfering
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Recombinant Fusion Proteins
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S100 Proteins
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S100 calcium binding protein A10
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potassium channel subfamily K member 3