Intracellular cleavage of an SSV coded gag-related protein

Simian sarcoma virus-transformed nonproducer cells (SSV-NP cells) express a viral-coded gag-related 65,000-dalton protein (p65), which is serologically and biochemically very similar to the SSAV gag precursor pr659gag. (H.-J. Thiel, T. J. Matthews, E. M. Broughton, K. J. Weinhold, D. P. Bolognesi, T. Graf, and H. Beug, Virology 114, 124–131, 1981). While p65 is not processed in SSV-NP cells, it becomes cleaved after superinfection with two heterologous helper viruses-an ecotropic mouse virus (FLV) as well as an amphotropic mouse virus (AP129). The cleavage results in a 30,000-dalton protein, which appears to be identical with the major internal protein of the homologous helper virus SSAV p30.