The La protein from human liver cells interacts specifically with the u-rich region in the hepatitis C virus 3 ' untranslated region

Objective: To identify cellular factors in human liver that interact with h epatitis C virus (HCV) 5' and 3' untranslated regions (UTRs) and therefore possibly are involved in the regulation of HCV transcription or translation . Methods: We prepared cytoplasmic extracts from human liver biopsy samples a nd fractionated cellular factors on ion exchange columns. The various fract ions from ion exchange columns were subjected to ultraviolet (UV) cross-lin king with radiolabeled HCV 5' and 3' UTR RNA probes. Results: Two major 45- and 46-kd proteins that interacted specifically with the I-ICV 5' and 3' UTR were identified. Using Western blot and immunoprec ipitation, these proteins were identified as the La antigen. Conclusion: Our results demonstrate that the La protein from human liver bi opsy cells interacts specifically with the U-rich region in the positive st rand of the HCV 3' UTR.