Low affinity of Trypanosoma brucei transferrin receptor to apotransferrin at pH 5 explains the fate of the ligand during endocytosis

FEBS Letters

Steverding, Dietmar¹  Maier, Alexander¹ 

[1] Hygiene-Institut der Ruprecht-Karls-Universität, Abteilung Parasitologie, Im Neuenheimer Feld 324, D-69120 Heidelberg, Germany

关键词: Transferrin receptor;    Transferrin;    Trypanosoma brucei;   

DOI  :  10.1016/0014-5793(96)01073-3

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Uptake of host transferrin (Tf) in Trypanosoma brucei is mediated by a heterodimeric, glycosyl-phosphatidylinositol-anchored receptor. After endocytosis, Tf is delivered to lysosomes where it is proteolytically degraded. So far, the sequence of events leading to ligand dissociation and degradation is undefined. We now show by Triton X-114 phase separation that iron-free Tf (apo-Tf) dissociates from the receptor at pH 5.0. The low affinity of apo-Tf for its receptor at pH 5.0 is confirmed by an apparent dissociation constant of 1.1 μM. The implications of this result on the mechanism of intracellular processing of Tf in trypanosomes are discussed.

【 授权许可】

Unknown