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. 1984 Aug;81(16):5155–5159. doi: 10.1073/pnas.81.16.5155

A Ca2+-activated channel from Xenopus laevis oocyte membranes reconstituted into planar bilayers.

G P Young, J D Young, A K Deshpande, M Goldstein, S S Koide, Z A Cohn
PMCID: PMC391656  PMID: 6089180

Abstract

Plasma membrane fractions from Xenopus laevis oocytes were incorporated into planar lipid bilayers. We show the existence of numerous Ca2+-activated nonspecific channels that are more permeable to anions. These channels are activated by Ca2+ at micromolar concentration but not by Mg2+, Zn2+, or Mn2+, even at millimolar concentrations. Decreasing Ca2+ concentration to less than 1 microM decreases the time of channel opening until channels close completely in the absence of Ca2+ and in the presence of EGTA. I- and Br- are more permeable through this channel than Cl-. The time during which the channels remain open is also voltage-dependent, with the channels switching off at higher voltages in both polarities. Single-channel activity shows a conductance of 380 pS in 1 M NaCl and 1 mM CaCl2, with an average open lifetime of 1.5 s at 40 mV. Similar channels are found in different stages of oocyte maturation. These observations support the hypothesis that an increase in oocyte-free Ca2+ activates directly these channels, and the resultant Cl- efflux forms the ionic basis for the fertilization potential in X. laevis.

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.

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