Transferrin Receptors in Developing Murine Erythroid Cells

Abstract

Summary. Techniques of cell separation were used to isolate murine erythroid cells at different stages of maturation. The number of transferrin receptors in these cell populations was assayed by measuring binding of ¹²⁵I-labelled transferrin. Nearly 23 times as many receptors were found in the least mature cells, chiefly pronormoblasts, as in reticulocytes. Iron transport, determined by measurement of the rate of ⁵⁹Fe uptake from ⁵⁹Fe-labelled transferrin, was proportional to the number of receptors at all stages of differentiation. Electron microscope radioautographic studies of the interaction of ¹²⁵I-labelled transferrin with erythroid precursor cells demonstrated that 15–35% of cell associated transferrin was intracellular in erythroid precursors.