Chromatographic and Electrophoretic Analysis of Viral Proteins from Hamster and Chicken Cells Transformed by Rous Sarcoma Virus

Several methods have been explored for the detection and characterization of viral proteins from soluble extracts of cells transformed by Rous sarcoma virus (RSV). Viral antigens have been analyzed after gel filtration in several solvents. In addition, immune complexes formed with virus-specific sera have been isolated by agarose gel filtration and by high- or low-speed centrifugation through sucrose solutions. Radioactive proteins from these immune complexes have been analyzed by gel filtration in 6 m guanidine hydrochloride or by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. Comparison with proteins from purified virus indicates the presence of two viral core proteins (gs1 and gs2) in the soluble fraction from virus-producing chicken cells. In the same fraction from RSV-transformed hamster cells (which do not produce virus), three gs proteins (gs1, gs2, and gs3) could be identified. The soluble viral gs proteins are strongly bound to at least two larger polypeptides in cell extracts. These polypeptides do not appear to be viral in origin and have the property of undergoing a time-dependent aggregation in the extracts. One of these cell-derived proteins, which is present in a variety of uninfected cell types, closely resembles actin.