Specific increase in thymidine transport at a permissive temperature in the rat kidney cells infected with srcts-Rous...

Thymidine transport was found to be increased two-fold at a permissive temperature in the cells of a normal rat kidney (NRK) line which was infected with a temperature-sensitive Rous sarcoma virus. This increase in thymidine transport was independent of cell density and coincided with the changes in cellular morphology that result from this temperature shift. A double reciprocal plot of the data demonstrated two saturable components (Km values of 60 microM and 250 microM at 39 degrees, non-permissive temperature) of the uptake of thymidine, and the drop of temperature (at 33 degrees, the permissive temperature for transformation) decreased Km to one half, but did not change Vmax. These results indicate that a qualitative alteration of thymidine transport took place in the presence of the active src gene product.