Binding sites for type C viral phosphoprotein on the viral RNA genome

The distribution of binding sites for R-MuLV p12 phosphoprotein on the viral genome has been examined. Ribonucleoprotein complexes formed using 3′-poly A-containing viral RNA fragments of varying lengths and $\text{in vitro}$ radioiodinated p12 protein have been analyzed by sedimentation velocity and buoyant density gradients. Binding sites for 2–3 molecules of p12 protein can be detected within the first 400 nucleotides from the 3′-poly A segment. The possible presence of binding sites near the middle of the genome (～2500 nucleotides from the 3′-end) and very close to the 5′-terminus (within the terminal 100–200 nucleotides) is also indicated.