Hemoglobin endocytosis in leishmania is mediated through a 46-kDa protein located in the flagellar pocket

Sengupta, Shantanu ; Tripathi, Jalaj ; Tandon, Ruchi ; Raje, Manoj ; Roy, Rajendra P. ; Basu, Sandip K. ; Mukhopadhyay, Amitabha (1999) Hemoglobin endocytosis in leishmania is mediated through a 46-kDa protein located in the flagellar pocket Journal of Biological Chemistry, 274 (5). pp. 2758-2765. ISSN 0021-9258

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Official URL: http://www.jbc.org/content/274/5/2758.abstract?sid...

Related URL: http://dx.doi.org/10.1074/jbc.274.5.2758

Abstract

Four lines of evidence indicate that a specific high affinity binding site on the surface of Leishmania donovani promastigotes mediates rapid internalization and degradation of hemoglobin. 1) Binding and uptake of125I-hemoglobin by Leishmania followed saturation kinetics and were competed by unlabeled hemoglobin but not by globin or hemin or other heme- or iron-containing proteins. 2) Immunogold labeling studies revealed that, at 4 °C, hemoglobin binding was localized in the flagellar pocket of the promastigotes. Indirect immunofluorescence assays showed that, at 37 °C, the bound hemoglobin in such cells entered an endocytic compartment within 2 min and dispersed throughout the cell body by 15 min. 3) After incubation with hemoglobin-gold conjugates at 25 °C or 37°C, the particles accumulated in discrete intracellular vesicles. 4) A single biotinylated protein of 46 kDa was revealed when solubilized membranes from surface biotinylated intact Leishmania adsorbed by hemoglobin-agarose beads were subjected to SDS-polyacrylamide gel electrophoresis and Western blotting with avidin-horseradish peroxidase. Considered together, these data indicate that this 46-kDa protein on the cell surface of L. donovani promastigotes mediates the binding of hemoglobin and its rapid internalization through a vesicular pathway characteristic of receptor-mediated endocytosis.

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Source:Copyright of this article belongs to The American Society for Biochemistry and Molecular Biology.
ID Code:52407
Deposited On:03 Aug 2011 14:03
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