Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

We report an ion channel in the plasma membrane of unfertilized oocytes of the ascidian Ciona intestinalis that is directly gated by the second messenger ADP-ribose. The ion channel is permeable to Ca2+ and Na+ and is characterized by a reversal potential between 0 and +20 mV and a unitary conductance of 140 pS. Preinjection of the Ca2+ chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) or antagonists of intracellular Ca2+ release channels into oocytes did not inhibit the ADP-ribose current, demonstrating that the channel is activated in a Ca2+-independent manner. Both the fertilization current and the current induced by the injection of nicotinamide nucleotides are blocked by nicotinamide, suggesting that the ADP-ribose channel is activated at fertilization in a nicotinamide-sensitive manner. These data suggest that ascidian sperm trigger the hydrolysis of nicotinamide nucleotides in the oocyte to ADP-ribose and that this mechanism is responsible for the production of the fertilization current.

Original publication

DOI

10.1152/ajpcell.1998.275.5.C1277

Type

Journal article

Journal

Am J Physiol

Publication Date

11/1998

Volume

275

Pages

C1277 - C1283

Keywords

Adenosine Diphosphate Ribose, Animals, Calcium, Cell Membrane Permeability, Chelating Agents, Ciona intestinalis, Egtazic Acid, Electric Conductivity, Female, Fertilization, In Vitro Techniques, Ion Channel Gating, Ion Channels, Membrane Potentials, NAD, NADP, Niacinamide, Oocytes, Patch-Clamp Techniques, Sodium