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The trafficking and activity of endosomes relies on the exchange of chloride ions and protons by members of the CLC family of chloride channels and transporters; mutations of the genes encoding these transporters are associated with numerous diseases. Despite their critical roles, the mechanisms by which CLC transporters are regulated are poorly understood. Here we show that two related accessory β-subunits, TMEM9 and TMEM9B, directly interact with ClC-3, ClC-4 and ClC-5. Cryo-electron microscopy structures reveal that TMEM9 inhibits ClC-3 by sealing the cytosolic entrance to the Cl ion pathway. Unexpectedly, we find that phosphatidylinositol 3,5-bisphosphate (PtdIns(3,5)P) stabilizes the interaction between TMEM9 and ClC-3 and is required for proper regulation of ClC-3 by TMEM9. Collectively, our findings reveal that TMEM9 and PtdIns(3,5)P collaborate to regulate endosomal ion homeostasis by modulating the activity of ClC-3.
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http://dx.doi.org/10.1038/s41594-025-01617-2 | DOI Listing |
Nat Struct Mol Biol
July 2025
Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
The trafficking and activity of endosomes relies on the exchange of chloride ions and protons by members of the CLC family of chloride channels and transporters; mutations of the genes encoding these transporters are associated with numerous diseases. Despite their critical roles, the mechanisms by which CLC transporters are regulated are poorly understood. Here we show that two related accessory β-subunits, TMEM9 and TMEM9B, directly interact with ClC-3, ClC-4 and ClC-5.
View Article and Find Full Text PDFFront Pharmacol
June 2025
Department of Urology, The Second Affiliated Hospital of Kunming Medical University, Kunming, Yunnan, China.
Objective: This study aims to identify circulating proteins causally associated with erectile dysfunction (ED) using Mendelian randomization (MR) analysis.
Methods: We utilized two of the largest multi-center proteomics databases as exposures and the FinnGen database as the outcome source. A large-scale two-sample MR analysis, including coloc colocalization analysis and SMR (Summary data-based Mendelian Randomization) analysis, was conducted to evaluate the reliability of proteomic effects on ED outcomes.
Nature
July 2025
Department of Cell Biology, Harvard Medical School, Boston, MA, USA.
Early or sorting endosomes are dynamic organelles that play key roles in proteome control by triaging plasma membrane proteins for either recycling or degradation in the lysosome. These events are coordinated by numerous transiently associated regulatory complexes and integral membrane components that contribute to organelle identity during endosome maturation. Although a subset of the several hundred protein components and cargoes known to associate with endosomes have been studied at the biochemical and/or structural level, interaction partners and higher-order molecular assemblies for many endosomal components remain unknown.
View Article and Find Full Text PDFNat Commun
April 2025
Leibniz-Forschungsinstitut für Molekulare Pharmakologie (FMP), Berlin, Germany.
The function of endosomes critically depends on their ion homeostasis. A crucial role of luminal Cl, in addition to that of H, is increasingly recognized. Both ions are transported by five distinct endolysosomal CLC chloride/proton exchangers.
View Article and Find Full Text PDFbioRxiv
March 2025
Structural Biology Program, Memorial Sloan Kettering Cancer Center; New York, NY, USA.
The trafficking and activity of endosomes relies on the exchange of chloride ions and protons by members of the CLC family of chloride channels and transporters, whose mutations are associated with numerous diseases. Despite their critical roles, the mechanisms by which CLC transporters are regulated are poorly understood. Here, we show that two related accessory β-subunits, TMEM9 and TMEM9B, directly interact with ClC-3, -4 and -5.
View Article and Find Full Text PDF