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| Foskett,J. Kevin; Mak,D.-O. Daniel. |
| The InsP3R Ca2+-release channel has biphasic dependence on cytoplasmic free Ca2+ concentration ([Ca2+]i). InsP3 activates gating primarily by reducing high [Ca2+]i inhibition. To determine whether relieving Ca2+ inhibition is sufficient for activation, we examined single-channels in low [Ca2+]i in the absence of InsP3 by patch clamping isolated Xenopus oocyte nuclei. For both endogenous Xenopus type 1 and recombinant rat type 3 InsP3R channels, spontaneous InsP3-independent activities with low open probability Po (~ 0.03) were observed in [Ca2+]i < 5 nM, whereas none were observed in 25 nM Ca2+. These results establish the half-maximal inhibitory [Ca2+]i in the absence of InsP3 and demonstrate that the channel can be active when all of its... |
| Tipo: Journal article |
Palavras-chave: InsP3 receptor; Calcium release channel; Calcium; Ion channel; Model. |
| Ano: 2004 |
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-97602004000400004 |
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