Evidence for a Functional Change in the Plasma Membrane of Murine Sarcoma Virus-infected Mouse Embryo Cells

Abstract

Enhancementof sugar uptake occurs in murine sarcoma virus-infected mouse cells at the time of transformation.Direct analysis of the sugar transport and transport-associated phosphorylation system of mouse cells infected with the Harvey strain of MSV was performed with 2-deoxy-Dglucose-14C.It was shown that 2-deoxy-D-glucose-14C was taken up at various concentrations (10m2 to 10e6 M) at a greater rate and was transported with a lower K, (21.0 to 23.3 x 10d4 M for uninfected and 3.5 to 5.0 X 10v4 M for infected cells) and higher IrmllX (18.2 to 19.2 nmoles per mg of protein per min at 37" for uninfected and 52.3 to 83.5 nmoles per mg of protein per min for infected cells) in the infected cells.The transported substrate was found mainly as a phosphorylated product, 2-deoxy-D-glucose 6-phosphate.The increased phosphorylation of 2-deoxy-D-glucose-14C by the infected cells was obtained only with intact cells, but not with cell homogenates, indicating that this phosphorylation is not due to increased intracellular hexokinase activity but rather based on a membrane-bound transport system.These data support the hypothesis that alterations in a plasma membrane sugar transport (penetration plus phosphorylation) system occurred during cellular transformation by murine sarcoma virus.