Cation channel sperm-associated targeting subunit tau (CTSRT, also known as Amyotrophic lateral sclerosis 2 chromosomal region candidate gene 11 and C2 calcium-dependent domain-containing protein 6) has been identified in mice as an auxiliary component of the CatSper complex, which is involved in sperm cell hyperactivation. Sperm cell hyperactivation is required for sperm motility, essential late in the preparation of sperm fertilisation [1]. This protein is key for CatSper flagellar targeting and trafficking into the quadrilinear nanodomains as it links the channel-carrying vesicles ans motor proteins in elongating flagella.

1: C2cd6-encoded CatSpertau targets sperm calcium channel to Ca(2+) signaling domains in the flagellar membrane. Hwang JY, Wang H, Lu Y, Ikawa M, Chung JJ; Cell Rep. 2022;38:110226. PMID:34998468