Structural highlights
Disease
[TM175_HUMAN] Disease susceptibility may be associated with variations affecting the gene represented in this entry. TMEM175 defects result in unstable lysosomal pH, leading to decreased lysosomal catalytic activity, decreased glucocerebrosidase activity, impaired autophagosome clearance by the lysosome and decreased mitochondrial respiration (PubMed:28193887).[1]
Function
[TM175_HUMAN] Organelle-specific potassium channel specifically responsible for potassium conductance in endosomes and lysosomes. Forms a potassium-permeable leak-like channel, which regulates lumenal pH stability and is required for autophagosome-lysosome fusion. Constitutes the major lysosomal potassium channel.[2] [3]
Publication Abstract from PubMed
Transmembrane protein 175 (TMEM175) is a K(+)-selective ion channel expressed in lysosomal membranes, where it establishes a membrane potential essential for lysosomal function and its dysregulation is associated with the development of Parkinson's Disease. TMEM175 is evolutionarily distinct from all known channels, predicting novel ion-selectivity and gating mechanisms. Here we present cryo-EM structures of human TMEM175 in open and closed conformations, enabled by resolutions up to 2.6 A. Human TMEM175 adopts a homodimeric architecture with a central ion-conduction pore lined by the side chains of the pore-lining helices. Conserved isoleucine residues in the center of the pore serve as the gate in the closed conformation. In the widened channel in the open conformation, these same residues establish a constriction essential for K(+) selectivity. These studies reveal the mechanisms of permeation, selectivity and gating and lay the groundwork for understanding the role of TMEM175 in lysosomal function.
Gating and selectivity mechanisms for the lysosomal K(+) channel TMEM175.,Oh S, Paknejad N, Hite RK Elife. 2020 Mar 31;9. pii: 53430. doi: 10.7554/eLife.53430. PMID:32228865[4]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Jinn S, Drolet RE, Cramer PE, Wong AH, Toolan DM, Gretzula CA, Voleti B, Vassileva G, Disa J, Tadin-Strapps M, Stone DJ. TMEM175 deficiency impairs lysosomal and mitochondrial function and increases alpha-synuclein aggregation. Proc Natl Acad Sci U S A. 2017 Feb 28;114(9):2389-2394. doi:, 10.1073/pnas.1616332114. Epub 2017 Feb 13. PMID:28193887 doi:http://dx.doi.org/10.1073/pnas.1616332114
- ↑ Cang C, Aranda K, Seo YJ, Gasnier B, Ren D. TMEM175 Is an Organelle K(+) Channel Regulating Lysosomal Function. Cell. 2015 Aug 27;162(5):1101-12. doi: 10.1016/j.cell.2015.08.002. PMID:26317472 doi:http://dx.doi.org/10.1016/j.cell.2015.08.002
- ↑ Lee C, Guo J, Zeng W, Kim S, She J, Cang C, Ren D, Jiang Y. The lysosomal potassium channel TMEM175 adopts a novel tetrameric architecture. Nature. 2017 Jul 27;547(7664):472-475. doi: 10.1038/nature23269. Epub 2017 Jul, 19. PMID:28723891 doi:http://dx.doi.org/10.1038/nature23269
- ↑ Oh S, Paknejad N, Hite RK. Gating and selectivity mechanisms for the lysosomal K(+) channel TMEM175. Elife. 2020 Mar 31;9. pii: 53430. doi: 10.7554/eLife.53430. PMID:32228865 doi:http://dx.doi.org/10.7554/eLife.53430
