Increased glucose transport in ras-transformed fibroblasts: A possible role for N-glycosylation of GLUT1

2-Deoxyglucose uptake was enhanced in ts371 MiMuSV-NRK cells when growing at the permissive temperature to allow the expression of a transforming p21 ras protein. This change is due to a decrease in the K-m by approximately 2.5-fold without affecting the V-max of the transporter. The amount of the GLUT1 glucose transporter dit not increase as deduced from imnunoblot experiments on total membranes. Nevertheless, ras-transformed GLUT1 displays a higher molecular mass due to an increased N-glycosylation of the protein. Experiments made in tunicamycin-treated cells indicates that a higher glycosylation is responsible for the increase in 2-deoxyglucose uptake in ras-transformed cells. (C) 1997 Federation of European Biochemical Societies.