The nuclear pore complex protein, Ran-binding protein 2 (Ran BP-2 or Nup358), contains four Ran-binding domains. Ran BP-2 is a large scaffold cyclophilin-related protein expressed in photoreceptor cells. Ran BP-2 localization at cytoplasmic fibrils emanating from the nuclear pore complex and interaction with the Ran-GTPase support its role in nucleocytoplasmic transport processes. In humans, the Ran BP-2 gene is partially duplicated in a gene cluster and lies in a hot spot for recombination on chromosome 2q. This genetic heterogeneity renders further significance of this genomic region in human disease due to its possible involvement in genetically linked disorders such as juvenile nephronophthisis, congenital hepatic fibrosis and chorioretinal dysplasia.