2. Academic Validation
  3. TPC proteins are phosphoinositide- activated sodium-selective ion channels in endosomes and lysosomes

TPC proteins are phosphoinositide- activated sodium-selective ion channels in endosomes and lysosomes

  • Cell. 2012 Oct 12;151(2):372-83. doi: 10.1016/j.cell.2012.08.036.
Xiang Wang 1,  Xiaoli Zhang,  Xian-Ping Dong,  Mohammad Samie,  Xinran Li,  Xiping Cheng,  Andrew Goschka,  Dongbiao Shen,  Yandong Zhou,  Janice Harlow,  Michael X Zhu,  David E Clapham,  Dejian Ren,  Haoxing Xu
Affiliations

Affiliation

  • 1 Department of Molecular, Cellular, and Developmental Biology, University of Michigan, 3089 Kraus Natural Science Building, 830 North University Avenue, Ann Arbor, MI 48109, USA.
PMID: 23063126 DOI: 10.1016/j.cell.2012.08.036
Abstract

Mammalian two-pore channel proteins (TPC1, TPC2; TPCN1, TPCN2) encode ion channels in intracellular endosomes and lysosomes and were proposed to mediate endolysosomal calcium release triggered by the second messenger, nicotinic acid adenine dinucleotide phosphate (NAADP). By directly recording TPCs in endolysosomes from wild-type and TPC double-knockout mice, here we show that, in contrast to previous conclusions, TPCs are in fact sodium-selective channels activated by PI(3,5)P(2) and are not activated by NAADP. Moreover, the primary endolysosomal ion is Na(+), not K(+), as had been previously assumed. These findings suggest that the organellar membrane potential may undergo large regulatory changes and may explain the specificity of PI(3,5)P(2) in regulating the fusogenic potential of intracellular organelles.

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