ATP depletion causes translational immobilization of cell surface transferrin receptors in K562 cells

We have used quantitative fluorescence microscopy and fluorescence photobleaching recovery to examine the role of metabolic energy in the translational movement of transferrin receptors in the plasma membrane of K562 erythroleukemia cells. Cellular ATP depletion caused a significant decrease in the translational mobility of cell surface transferrin receptors and a significant increase in the number of receptors on the cell surface. ATP repletion restored receptor translational mobility and cell surface expression to control values. Inhibition of ATP hydrolases by orthovanadate also immobilized cell surface transferrin receptors and altered cell surface receptor expression, in a concentration-dependent manner. Vanadate-induced changes in receptor mobility and cell surface expression were reversible upon washing out the drug. Cellular ATP depletion did not affect the translational mobility of plasma membrane glycophorins or a fluorescent phospholipid analogue. We conclude that the translational movement of cell surface transferrin receptors specifically requires metabolic energy and ATP hydrolysis.