Calcium has long been known to be important in sperm function, but a full understanding of the molecular mechanisms of its action has remained elusive. In October 11 Nature, Dejian Ren and colleagues from Howard Hughes Medical Institute and Harvard Medical School describe a new cation channel, CatSper, which is vital to cAMP-mediated Ca²⁺ influx in sperm, sperm motility and fertilization.

Ren et al. analyzed DNA for sequences that might code for known voltage-gated calcium channels and found a gene that was only expressed in testis. The gene encodes a cation channel (CatSper, cation channel of sperm) located specifically in the principal piece of the sperm tail. To test the function of CatSper, they created mice with targeted disruption of the gene and found that all male mice were sterile, but otherwise normal. Sperm from CatSper^-/- mice were incapable of cyclic-AMP-induced Ca²⁺ influx and...