CBY2, or Spermatid associated, is a human gene encoded by SPERT. It may also be known as: Spermatid-associated protein; Protein chibby homolog 2; spermatid flower-like structure protein; testis specific leucine zipper protein nurit; chibby homolog 2 (Drosophila); NURIT. The encoded protein has an amino acid length of 448 and a mass of 51.6 kDa. Other isoforms may exist. CBY2 is a member of the Chibby family, SPERT subfamily. Homologs of this gene exist in other organisms, including: Mouse.