Abstract
Genetic and biochemical analyses of the 5'' noncoding region of poliovirus have indicated the importance of this region in both translation and amplification of the viral RNA. The role of the cellular machinery required for these events is just beginning to be revealed. Using an RNA gel retention assay, we have identified a cellular 50-kDa protein that forms a specific complex with a stable stem-loop structure present in the viral 5'' noncoding region. The formation of the RNA-protein complex is dependent on the availability of free sulfhydryl groups in the protein. The possible involvement of this RNA-protein complex in the regulation of viral gene expression is discussed.