This family of proteins is found in eukaryotes. Proteins in this family are typically between 168 and 410 amino acids in length. This family is the N terminal end of the sex determination protein of many different animals. It plays a role in the gender determination of around 20% of all animals.

1: The gene csd is the primary signal for sexual development in the honeybee and encodes an SR-type protein. Beye M, Hasselmann M, Fondrk MK, Page RE, Omholt SW; Cell. 2003;114:419-429. PMID:12941271