Editors' ChoiceIon Channels

Two Calcium Channels at Work in Sperm

Science's STKE  09 May 2000:
Vol. 2000, Issue 31, pp. tw4
DOI: 10.1126/stke.2000.31.tw4

Upon contact with the ZP3 glycoprotein of a mammalian egg's outer coating, the zona pellucida, the intracellular calcium concentration in the associated sperm rises, stimulating the exocytic acrosome reaction that drives fertilization. O'Toole et al. report that in mouse sperm, after the known transient calcium influx that occurs through low voltage-activated-type channels, a second sustained calcium influx occurs through calcium store-depleted activated channels. Both transient and sustained calcium influxes were necessary for the acrosome reaction to occur. Other voltage-gated calcium channels were ruled out through the use of specific antagonists. The requirement for a transient calcium entry before a sustained calcium response to ZP3 stimulation is not yet clear.

O'Toole, C.M.B., Arnoult, C., Darszon, A., Steinhardt, R.A., and Florman, H.F. (2000) Ca2+ entry through store-operated channels in mouse sperm is initiated by egg ZP3 and drives the acrosome reaction. Mol. Biol. Cell 11: 1571-1584. [Abstract] [Full Text]

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