Acquisition of lipoproteins in the procyclic form of Trypanosoma brucei

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• 作者：Gwo-Shu Lee ; Mary ; Yen ; Frances T. ; Zhang ; Yuhong ; Bihain ; Bernard E.
• 关键词：Trypanosoma brucei ; High density lipoprotein ; CRAM ; cysteine rich acidic trans-membrane protein ; HDL ; high density lipoprotein ; IDL ; intermediate density lipoprotein ; LDL ; low density lipoprotein ; VLDL ; very low density lipoprotein
• 刊名：Molecular and Biochemical Parasitology
• 出版年：1999
• 出版时间：May 25, 1999
• 年：1999
• 卷：100
• 期：2
• 页码：153-162
• 全文大小：272 K

文摘

The procyclic form of Trypanosoma brucei binds and internalizes bovine high density lipoprotein (HDL) particles in a saturable process; the binding and uptake of ¹²⁵I-labeled HDL are inhibited by excess unlabeled HDL. We calculated that each procyclic trypanosome exposes ≈1.0×10⁶ binding sites for bovine HDL, with an equilibrium dissociation constant (K_d) of ≈1.26×10⁻⁷ M. Uptake of HDL particles does not occur at 4°C. At 28°C, a significant amount of the internalized HDL particles were efficiently degraded through a process that is sensitive to the presence of 50 μM chloroquine. These results suggested that the uptake of HDL particles in procyclic T. brucei may occur via receptor mediated endocytosis, leading to proteolytic degradation of the particles in an acidic and endocytic compartment.