Figure 1.

Transferrin receptor expressed on cell surface binds transferrin bound to two iron atoms. The transferrin receptor-transferrin complex is internalised; iron dissociates and moves into cytosol; and transferrin receptor-transferrin complex moves back to plasma membrane and dissociates (TfR=transferrin receptor; monoFeTf=transferrin bound to one iron atom; diFeTf=transferrin bound to two iron atoms; apoTf=transferrin lacking bound iron; H⁺=hydrogen ion)