The store-operated calcium entry pathways in human carcinoma A431 cells: functional properties and activation mechanisms.
J Gen Physiol
; 122(1): 81-94, 2003 Jul.
Article
em En
| MEDLINE
| ID: mdl-12835472
ABSTRACT
Activation of phospholipase C (PLC)-mediated signaling pathways in nonexcitable cells causes the release of Ca2+ from intracellular Ca2+ stores and activation of Ca2+ influx across the plasma membrane. Two types of Ca2+ channels, highly Ca2+-selective ICRAC and moderately Ca2+-selective ISOC, support store-operated Ca2+ entry process. In previous patch-clamp experiments with a human carcinoma A431 cell line we described store-operated Imin/ICRACL plasma membrane Ca2+ influx channels. In the present paper we use whole-cell and single-channel recordings to further characterize store-operated Ca2+ influx pathways in A431 cells. We discovered that (a) ICRAC and ISOC are present in A431 cells; (b) ICRAC currents are highly selective for divalent cations and fully activate within 150 s after initiation of Ca2+ store depletion; (c) ISOC currents are moderately selective for divalent cations (PBa/PCs = 14.5) and require at least 300 s for full activation; (d) ICRAC and ISOC currents are activated by PLC-coupled receptor agonists; (e) ISOC currents are supported by Imin/ICRACL channels that display 8.5-10 pS conductance for sodium; (f) ICRAC single channel conductance for sodium is estimated at 0.9 pS by the noise analysis; (g) Imin/ICRACL channels are activated in excised patches by an amino-terminal fragment of InsP3R1 (InsP3R1N); and (h) InsP3 binding to InsP3R1N is necessary for activation of Imin/ICRACL channels. Our findings provide novel information about store-operated Ca2+ influx pathways in A431 cells.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Canais de Cálcio
/
Transdução de Sinais
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Ativação do Canal Iônico
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Sinalização do Cálcio
/
Potenciais da Membrana
Limite:
Humans
Idioma:
En
Revista:
J Gen Physiol
Ano de publicação:
2003
Tipo de documento:
Article
País de afiliação:
Estados Unidos