1. Cooperative endocytosis of the endosomal SNARE protein syntaxin-8 and the potassium channel TASK-1.
- Author
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Renigunta V, Fischer T, Zuzarte M, Kling S, Zou X, Siebert K, Limberg MM, Rinné S, Decher N, Schlichthörl G, and Daut J
- Subjects
- Animals, CHO Cells, COS Cells, Chlorocebus aethiops, Cricetinae, Cricetulus, Endosomes metabolism, Female, HeLa Cells, Humans, Nerve Tissue Proteins chemistry, Potassium Channels, Tandem Pore Domain chemistry, Protein Interaction Domains and Motifs, Qa-SNARE Proteins chemistry, Xenopus laevis, Endocytosis, Nerve Tissue Proteins metabolism, Potassium Channels, Tandem Pore Domain metabolism, Qa-SNARE Proteins metabolism
- Abstract
The endosomal SNARE protein syntaxin-8 interacts with the acid-sensitive potassium channel TASK-1. The functional relevance of this interaction was studied by heterologous expression of these proteins (and mutants thereof) in Xenopus oocytes and in mammalian cell lines. Coexpression of syntaxin-8 caused a fourfold reduction in TASK-1 current, a corresponding reduction in the expression of TASK-1 at the cell surface, and a marked increase in the rate of endocytosis of the channel. TASK-1 and syntaxin-8 colocalized in the early endosomal compartment, as indicated by the endosomal markers 2xFYVE and rab5. The stimulatory effect of the SNARE protein on the endocytosis of the channel was abolished when both an endocytosis signal in TASK-1 and an endocytosis signal in syntaxin-8 were mutated. A syntaxin-8 mutant that cannot assemble with other SNARE proteins had virtually the same effect as wild-type syntaxin-8. Total internal reflection fluorescence microscopy showed formation and endocytosis of vesicles containing fluorescence-tagged clathrin, TASK-1, and/or syntaxin-8. Our results suggest that the unassembled form of syntaxin-8 and the potassium channel TASK-1 are internalized via clathrin-mediated endocytosis in a cooperative manner. This implies that syntaxin-8 regulates the endocytosis of TASK-1. Our study supports the idea that endosomal SNARE proteins can have functions unrelated to membrane fusion., (© 2014 Renigunta et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).)
- Published
- 2014
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