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- Title
A K<sup>+</sup>-selective cGMP-gated ion channel controls chemosensation of sperm.
- Authors
Strünker, Timo; Weyand, Ingo; Bönigk, Wolfgang; Van, Qui; Loogen, Astrid; Brown, Joel E.; Kashikar, Nachiket; Hagen, Volker; Krause, Eberhard; Kaupp, U. Benjamin
- Abstract
Eggs attract sperm by chemical factors, a process called chemotaxis. Sperm from marine invertebrates use cGMP signalling to transduce incident chemoattractants into changes in the Ca2+ concentration in the flagellum, which control the swimming behaviour during chemotaxis. The signalling pathway downstream of the synthesis of cGMP by a guanylyl cyclase is ill-defined. In particular, the ion channels that are involved in Ca2+ influx and their mechanisms of gating are not known. Using rapid voltage-sensitive dyes and kinetic techniques, we record the voltage response that is evoked by the chemoattractant in sperm from the sea urchin Arbacia punctulata. We show that the chemoattractant evokes a brief hyperpolarization followed by a sustained depolarization. The hyperpolarization is caused by the opening of K+-selective cyclic-nucleotide-gated (CNG) channels in the flagellum. Ca2+ influx commences at the onset of recovery from hyperpolarization. The voltage threshold of Ca2+ entry indicates the involvement of low-voltage-activated Cav channels. These results establish a model of chemosensory transduction in sperm whereby a cGMP-induced hyperpolarization opens Cav channels by a 'recovery-from-inactivation' mechanism and unveil an evolutionary kinship between transduction mechanisms in sperm and photoreceptors.
- Subjects
CHEMOTAXIS; SPERM-ovum interactions; PHOTORECEPTORS; CYCLIC nucleotides; ION channels; CELLULAR signal transduction; ARBACIA punctulata
- Publication
Nature Cell Biology, 2006, Vol 8, Issue 10, p1149
- ISSN
1465-7392
- Publication type
Article
- DOI
10.1038/ncb1473