NYN Domain And Retroviral Integrase Containing Protein (NYNRIN)

CGIN1 proteins contain an NYN domain, retroviral RNase H and integrase domains, and a domain of unknown function (CGIN1 domain) that is also present in two other genes. CGIN1 derives from the fusion of a KIAA0323-like gene with retroviral sequences, which occurred prior to the marsupial-eutherian split. Sequence and structural analyses indicate that the CGIN1 integrase domain is inactive but still retains the 3D folding observed in retroviral integrases. CGIN1 may contribute to retroviral resistance in mammals by regulating the ubiquitination of viral proteins. The NYN domain proteins of eukaryotes are regulated by monoubiquitination. Given the localization of Nedd4-BP1 to punctuate nuclear bodies, it is likely that they are parts of nuclear RNA-processing complexes that are dependent on monoubiquitination for their assembly.