Polypyrimidine tract-binding protein (PTB) interacts with three distinct regions of the HCV 5' noncoding region and is functionally required for internal initiation of translation.
PTB interacts with multiple sites on the HCV 5'NCR and is functionally required, along with associated factors, for internal initiation of translation.
Initiation of translation of the human hepatitis C virus (HCV) RNA genome occurs by internal ribosome entry into the 5' noncoding region (5'NCR) in a cap-independent manner. The internal ribosome entry site of the HCV 5'NCR has been previously defined to encompass almost the entire 5'NCR. Here we report the interaction of polypyrimidine tract-binding protein (PTB) at three distinct regions within the 5'NCR by UV cross-linking assays. All three regions contain a consensus polypyrimidine tract motif. The evidence for the interaction of recombinant PTB at multiple sites within the 5'NCR is based on the use of 5'NCR mutants as competitors and by direct UV cross-linking of the mutant RNAs. Furthermore, the PTB isomers from HeLa nuclear extracts interact with the HCV 5'NCR, as shown by immunoprecipitation of a UV cross-linked complex with anti-PTB serum. Immunodepletion of PTB from translation lysates suggested the functional requirement for PTB during translation initiation of the HCV RNA. Addition of purified PTB to immunodepleted lysates did not restore translation mediated by the HCV 5'NCR, indicating the requirement of PTB-associated factors that were removed during immunodepletion.
Ali et al. (Sun,) conducted a other in Hepatitis C virus (HCV). Polypyrimidine tract-binding protein (PTB) was evaluated on Interaction with HCV 5'NCR and translation initiation. Polypyrimidine tract-binding protein (PTB) interacts with three distinct regions of the HCV 5' noncoding region and is functionally required for internal initiation of translation.
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