hnRNP C and polypyrimidine tract-binding protein specifically interact with the pyrimidine-rich region within the 3 ' NTR of the HCV RNA genome

Like other members of the Flaviviridae family, the 3' non-translated region (NTR) of the hepatitis C virus (HCV) is believed to function in the initia tion and regulation of viral RNA replication by interacting with components of the viral replicase complex. To investigate the possibility that host c omponents may-also participate in this process, we used UV cross-linking as says to determine if any cellular proteins could bind specifically to the 3 'NTR RNA. We demonstrate the specific interaction of two host proteins with the extensive pyrimidine-rich region within the HCV 3'NTR. One host protei n migrates as a doublet with a molecular weight of 57 kDa and is immunoreac tive with antisera specific for polypyrimidine tract-binding protein-(PTB), and the other protein (35 kDa) is recognized by a monoclonal antibody spec ific for heterogeneous nuclear ribonucleoprotein C (hnRNP C), These results suggest that recognition of the large pyrimidine-rich region by PTB and hn RNP C may play a role in the initiation and/or regulation of HCV RNA replic ation.