title: Rapid lateral diffusion of the variant surface glycoprotein in the coat of Trypanosoma brucei.
abstract: The membrane form of the variant surface glycoprotein (mfVSG) is anchored in the plasma membrane of Trypanosoma brucei by a dimyristoylphosphatidylinositol residue connected via a glycan to the COOH-terminal amino acid. The glycoprotein molecules are tightly packed, forming a coat that is impenetrable to lytic serum components. Lateral diffusion of mfVSG was measured by the fluorescence recovery after photobleaching technique. mfVSG labeled on the cell surface with rhodamine-conjugated anti-VSG Fab fragments showed a diffusion coefficient of 1 X 10(-10) cm2/s at 37 degrees C and of 0.7 X 10(-10) cm2/s at 27 degrees C. About 80% of the molecules were mobile. Affinity-purified mfVSG molecules implanted into the plasma membrane of baby hamster kidney cells exhibited a similar mobility to that found in the trypanosome coat [D = (0.4-0.7) X 10(-10) cm2/s at 4 degrees C]. Phospholipid mobility in the plasma membrane of trypanosomes was characterized by a diffusion coefficient of 2.2 X 10(-9) cm2/s at 37 degrees C. It is concluded that mfVSG mobility in the surface coat of the parasite is rapid and comparable to that of other membrane-bound glycoproteins but slower than that of phospholipids.
authors: Max-Planck-Institut für Biologie, Tübingen, FRG.
authors: R
authors: R
authors: Bülow
authors: P
authors: P
authors: Overath
authors: J
authors: J
authors: Davoust
mesh_terms: D000818:Animals; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D004058:Diffusion; D004134:Dimyristoylphosphatidylcholine; D007140:Immunoglobulin Fab Fragments; D014346:Trypanosoma brucei brucei / Q000378:metabolism*; D014643:Variant Surface Glycoproteins, Trypanosoma / Q000276:immunology / Q000378:metabolism*
chemical_list: D007140:Immunoglobulin Fab Fragments; D014643:Variant Surface Glycoproteins, Trypanosoma; D004134:Dimyristoylphosphatidylcholine