Multiple forms of sarc gene proteins from Rous sarcoma virus RNA

In a previous study we were able to identify two proteins of 25,000 and 18,000 daltons that were made from RNA of transforming virions of Rous sarcoma virus (RSV) and that were missing from the translation products of a transformation-defective deletion mutant of RSV. In the present study we have separated RSV virion RNA on sucrose gradients and have determined that the two putative sarc gene products are synthesized as doublets from an mRNA of approximately 18 S. There also appear to be several other sizes of virion mRNA that direct the synthesis of other viral proteins. These data are discussed in terms of the structure of the RSV genome. In addition to the 25,000- and 18,000-dalton doublets, there also is a 60,000-dalton protein whose synthesis is directed by 18S viral RNA from transforming virion of RSV. Peptide mapping has shown that the 60,000- and 25,000-dalton doublet are structurally related. In addition, the use of two-dimensional gel electrophoresis has allowed us to resolve both bands of the 25,000-dalton doublet into several differently charged species.