TY - JOUR
T1 - Ca2+-activated Cl- current from human bestrophin-4 in excised membrane patches
AU - Tsunenari, Takashi
AU - Nathans, Jeremy
AU - Yau, King Wai
PY - 2006/6
Y1 - 2006/6
N2 - Bestrophins are a newly discovered family of Cl- channels, some members of which are activated by intracellular Ca2+. So far, all studies were carried out with whole-cell recordings from plasmid-transfected cultured cells, so it is unclear whether Ca2+ activates bestrophin through a metabolic mechanism or in a more direct way. We report here experiments that addressed this question with excised, inside-out membrane patches. We chose human bestrophin-4 (hBest4) for heterologous expression because it gave particularly large Cl- currents when expressed, thus allowing detection even in excised membrane patches. hBest4 gave a negligible Cl- current in a Ca2+-free solution on the cytoplasmic (bath) side, but produced a Cl- current that was activated by Ca 2+ in a dose-dependent manner, with a K1/2 of 230 nM. Thus, Ca 2+ appears to activate the bestrophin Cl- channel without going through a freely diffusible messenger or through protein phosphorylation. Because the activation and deactivation kinetics were very slow, however, we cannot exclude the involvement of a membrane-associated messenger.
AB - Bestrophins are a newly discovered family of Cl- channels, some members of which are activated by intracellular Ca2+. So far, all studies were carried out with whole-cell recordings from plasmid-transfected cultured cells, so it is unclear whether Ca2+ activates bestrophin through a metabolic mechanism or in a more direct way. We report here experiments that addressed this question with excised, inside-out membrane patches. We chose human bestrophin-4 (hBest4) for heterologous expression because it gave particularly large Cl- currents when expressed, thus allowing detection even in excised membrane patches. hBest4 gave a negligible Cl- current in a Ca2+-free solution on the cytoplasmic (bath) side, but produced a Cl- current that was activated by Ca 2+ in a dose-dependent manner, with a K1/2 of 230 nM. Thus, Ca 2+ appears to activate the bestrophin Cl- channel without going through a freely diffusible messenger or through protein phosphorylation. Because the activation and deactivation kinetics were very slow, however, we cannot exclude the involvement of a membrane-associated messenger.
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U2 - 10.1085/jgp.200609527
DO - 10.1085/jgp.200609527
M3 - Article
C2 - 16702355
AN - SCOPUS:33744470320
SN - 0022-1295
VL - 127
SP - 749
EP - 754
JO - Journal of General Physiology
JF - Journal of General Physiology
IS - 6
ER -