Bloodstream forms of Trypanosoma brucei require only small amounts of iron for growth.

Bloodstream forms of Trypanosoma brucei require transferrin (Tf) for growth. Uptake of Tf is mediated by a heterodimeric, glycosylphosphatidylinositol-anchored receptor. Competition studies of the uptake of iron-loaded Tf (holo-Tf) versus iron-free Tf (apo-Tf) showed that bloodstream-form trypanosomes required only small amounts of iron for growth. The competition experiments were possible as the trypanosome Tf receptor shows a similarly high affinity for both holo-Tf and apo-Tf. Calculations revealed that accumulation of about 40,000 iron atoms during 1 generation-doubling time was sufficient for parasite multiplication.