A putative ATP-activated Na+ channel involved in sperm-induced fertilization.
Extracellular application of adenosine triphosphate (ATP) to defolliculated Xenopus laevis oocytes activated a saturating inward current with a maximal amplitude E(max) of 2.4 +/- 0.2 microamperes and an apparent Michaelis constant of 197.6 micromolar. The current was carried predominantly by sodium ions and potently inhibited by amiloride, guanosine triphosphate (GTP), and its nonhydrolyzable analogs guanosine 5'-[beta,gamma-imido]triphosphate (GppNHp) and guanosine 5'-O-(3-thiotriphosphate). Likewise, in vitro fertilization using mature eggs and Xenopus sperm was inhibited by amiloride, GTP, and GppNHp. Hence, an ATP receptor on the egg membrane may be the recipient target for ATP originating in sperm, suggesting that an ATP-induced increase in sodium permeability mediates the initial sperm to egg signal in the fertilization process.
Department of Biological Chemistry, Hebrew University of Jerusalem, Israel.
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Kupitz
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Atlas
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology / Q000502:physiology*; D000584:Amiloride / Q000494:pharmacology; D000818:Animals; D005260:Female; D006160:Guanosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D066298:In Vitro Techniques; D008297:Male; D008564:Membrane Potentials / Q000502:physiology; D009865:Oocytes / Q000502:physiology; D011983:Receptors, Purinergic / Q000187:drug effects / Q000502:physiology; D015222:Sodium Channels / Q000502:physiology*; D013084:Sperm-Ovum Interactions / Q000502:physiology*; D014982:Xenopus laevis
D011983:Receptors, Purinergic; D015222:Sodium Channels; D000584:Amiloride; D006160:Guanosine Triphosphate; D000255:Adenosine Triphosphate