A comparison of the interaction of Chinese hamster fibroblasts with human and bovine transferrins, and conalbumin (chick-egg transferrin)

The iron requirement of a cell line of Chinese hamster fibroblasts is met more efficiently by human transferrin than by bovine transferrin or conalbumin. One possible explanation is that the binding of these transferrins to the Chinese hamster V79 cells may differ. Binding studies now show that the affinity of V79 cells for human transferrin is about 40 times greater than for bovine transferrin. Conalbumin has no detectable affinity for the human transferrin binding sites. Human apotransferrin has approximately one-sixth the affinity for the transferrin binding sites. The binding constant for the relation of human transferrin with the V79 cell is about 2.3·10⁶1· mole⁻¹, and the approximate number of binding sites per cell is 9 · 10⁵.