Leishmania major proteophosphoglycans exist as membrane-bound and soluble forms and localise to the cell membrane, the flagellar pocket and the lysosome.
The Leishmania proteophosphoglycan belongs to a family of heterogeneous polypeptides of unusual composition and structure. Here we demonstrate the presence in the parasite of a membrane-bound hydrophobic form of proteophosphoglycan, in addition to the previously described water-soluble form secreted into the culture medium. Phosphatidylinositol-specific phospholipase C treatment of the hydrophobic form of proteophosphoglycan converted it into a water-soluble form, confirming that it has a functional glycosylphosphatidylinositol-anchor, compatible with it being the product of the proteophosphoglycan1 gene. Immunofluorescence, immunoelectron microscopy and surface labelling showed that proteophosphoglycan expression was variable in individual cells but that it was present on the surface of both amastigotes and promastigotes, in the flagellar pocket, in endosomes and in the multi-vesicular tubule which is the newly described lysosome.
Foth
Bernardo
B
Department of Biochemistry, University of Melbourne, Melbourne, Victoria 3052, Australia.
Piani
Aline
A
Curtis
Joan M
JM
Ilg
Thomas
T
McConville
Malcolm
M
Handman
Emanuela
E
D000818:Animals; D019921:Biotinylation; D015153:Blotting, Western; D005407:Flagella / Q000378:metabolism; D017261:Glycosylphosphatidylinositols / Q000378:metabolism; D018320:Leishmania major / Q000378:metabolism* / Q000648:ultrastructure; D008247:Lysosomes / Q000378:metabolism; D008565:Membrane Proteins / Q000187:drug effects / Q000378:metabolism*; D016253:Microscopy, Immunoelectron; D011509:Proteoglycans / Q000187:drug effects / Q000378:metabolism*; D015800:Protozoan Proteins / Q000378:metabolism; D012995:Solubility; D010738:Type C Phospholipases / Q000494:pharmacology
D017261:Glycosylphosphatidylinositols; D008565:Membrane Proteins; C400527:Ppg1 protein, Leishmania; D011509:Proteoglycans; D015800:Protozoan Proteins; D010738:Type C Phospholipases