CN-IB, or 5'-nucleotidase, cytosolic IB, is a human gene encoded by NT5C1B. It may also be known as: Cytosolic 5'-nucleotidase 1B; cN1B; Autoimmune infertility-related protein; Cytosolic 5'-nucleotidase IB; cN-IB; AIRP. The encoded protein is an enzyme with an amino acid length of 610 and a mass of 68.8 kDa. CN-IB is a member of the 5'-nucleotidase type 3 family. Homologs of this gene exist in other organisms, including: Mouse, Rat, Chicken.