This entry represents Jiv (J-domain protein interacting with viral protein), a domain found in the DnaJ protein from eukaryotes. It can also be found in the N-terminal region of the pestivirus viral polypeptide. The viral protein interacts stably with non structural (NS) protein NS2, causing a conformational change in NS2-NS3 and stimulates NS2-NS3 cleavage in trans. Cleavage of NS2-NS3 increases cytopathogenicity and consequently aids viral replication. Jiv therefore acts as a regulating cofactor for NS2 auto-protease. The efficient release of NS3 from the viral polypeptide by Jiv is considered crucial to the pestivirus cytopathogenicity. In eukaryotes, it usually lies 40 residues downstream of DnaJ domain . However, the function of this domain in eukaryotes is still unknown.