A K+-selective cGMP-gated ion channel controls chemosensation of sperm

Nat Cell Biol. 2006 Oct;8(10):1149-54. doi: 10.1038/ncb1473. Epub 2006 Sep 10.


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 Ca(v) channels. These results establish a model of chemosensory transduction in sperm whereby a cGMP-induced hyperpolarization opens Ca(v) channels by a 'recovery-from-inactivation' mechanism and unveil an evolutionary kinship between transduction mechanisms in sperm and photoreceptors.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Arbacia / chemistry
  • Calcium / metabolism
  • Calcium Signaling / physiology*
  • Chemotaxis
  • Cyclic GMP / metabolism*
  • Guanylate Cyclase / metabolism
  • Ion Channel Gating*
  • Ion Channels*
  • Male
  • Potassium / metabolism*
  • Signal Transduction*
  • Spermatozoa / metabolism*


  • Ion Channels
  • Guanylate Cyclase
  • Cyclic GMP
  • Potassium
  • Calcium