%0 Journal Article
%@ 0021-9258
%A Sengupta, S
%A Tripathi, J
%A Tandon, R
%A Raje, Manoj
%A Roy, R P
%A Basu, S K
%A Mukhopadhyay, A
%D 1999
%F open:793
%I ASBMB
%J The Journal of biological chemistry
%N 5
%P 2758-65
%T Hemoglobin endocytosis in Leishmania is mediated through a 46-kDa protein located in the flagellar pocket.
%U http://crdd.osdd.net/open/793/
%V 274
%X 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 of 125I-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 degreesC, hemoglobin binding was localized in the flagellar pocket of the promastigotes. Indirect immunofluorescence assays showed that, at 37 degreesC, 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 degreesC or 37 degreesC, 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.
%Z Copyright of this article belongs to ASBMB.