新着情報

○TRICチャネルの発見　(2007. 7)

TRIC channels are essential for Ca2+ handling in intracellular stores Yazawa, M., Ferrante, C., Feng, J., Mio, K., Ogura, T., Zhang, M., Lin, P-H., Pan, P., Komazaki, S., Kato, K., Nishi, M., Zhao, X., Weisleder, N., Sato, C., Ma, J. and Takeshima, H (Nature 448, 78-82, 2007)

Cell signaling requires efficient Ca2+ mobilization from intracellular stores through Ca2+ release channels, as well as predicted counter movement of ions across the sarcoplasmic/endoplasmic reticulum (SR/ER) membrane to balance the transient negative potential generated by Ca2+ release. Ca2+ release channels were cloned more than 15 years ago, whereas the molecular identity of putative counter-ion channels remains unknown. Here we report two TRIC (trimeric intracellular cation) channel subtypes that are differentially expressed on intracellular stores in animal cell types. TRIC subtypes contain three proposed transmembrane segments and form homo-trimers with a bullet-like structure. Electrophysioloigcal measurements with purified TRIC preparations identify a monovalent cation-selective channel. In TRIC-knockout mice suffering embryonic cardiac failure, mutant cardiac myocytes display severe dysfunction in intracellular Ca2+ handling. The TRIC-deficient skeletal muscle SR shows reduced K+ permeability, as well as altered Ca2+ spark signaling and voltage-induced Ca2+ release. Therefore, TRIC channels likely act as counter-ion channels that function in synchronization with SR/ER Ca2+ release.

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