The sperm-specific K channel Slo3 is inhibited by albumin and steroids contained in reproductive fluids.

To locate and fertilize the egg, sperm probe the varying microenvironment prevailing at different stages during their journey across the female genital tract. To this end, they are equipped with a unique repertoire of mostly sperm-specific proteins. In particular, the flagellar Ca channel CatSper has come into focus as a polymodal sensor used by human sperm to register ligands released into the female genital tract.

Antiviral signalling by a cyclic nucleotide activated CRISPR protease.

CRISPR defence systems such as the well-known DNA-targeting Cas9 and the RNA-targeting type III systems are widespread in prokaryotes. The latter orchestrates a complex antiviral response that is initiated through the synthesis of cyclic oligoadenylates after recognition of foreign RNA. Among the large set of proteins that are linked to type III systems and predicted to bind cyclic oligoadenylates, a CRISPR-associated Lon protease (CalpL) stood out to us.