REG1 beta is a type I subclass member of the Reg gene family. The Reg gene family is a multigene family grouped into four subclasses, types I, II, III and IV based on the primary structures of the encoded proteins. REG1 beta highly similar to the REG1 alpha protein. The related REG1 alpha protein is associated with islet cell regeneration and diabetogenesis, and may be involved in pancreatic lithogenesis. Reg family members REG1 alpha, REGL, PAP and this gene are tandomly clustered on chromosome 2p12 and may have arisen from the same ancestral gene by gene duplication.