RNA synthesis by temperature-sensitive mutants of vesicular stomatitis virus, New Jersey serotype.

We report the results of studies using temperature-sensitive mutants of Rous sarcoma virus (ts RSV) to study the alterations in surface proteins occurring on transformation. A large external transformation-sensitive (LETS) protein is detected by lactoperoxidase-catalyzed iodination on normal chicken embryo fibroblasts (CEF) but is reduced on RSV-transformed cells. The LETS protein is temperature sensitive in ts RSV-infected CEF and the kinetics of the alterations occurring on shifts between permissive and restrictive temperature are reported. During reversion to normality on shift-up, the LETS protein appears at the surface quite rapidly and in parallel with the morphological changes, although the change is less rapid than that in glucose transport. On transformation during shift-down, the disappearance of the LETS protein lags behind the morphological change. Cycloheximide does not inhibit reappearance of iodinatable LETS protein on shift-up, suggesting that the LETS protein is synthesized in transformed cells, although it is not present at the surface. Hypotheses to explain the absence of the LETS protein at the surface are discussed and evidence is presented for an increased rate of turnover after transformation.