R. Giordano et al., AN ACIDIC COMPONENT OF THE HETEROGENEOUS TC-85 PROTEIN FAMILY FROM THE SURFACE OF TRYPANOSOMA-CRUZI IS A LAMININ-BINDING GLYCOPROTEIN, Molecular and biochemical parasitology, 65(1), 1994, pp. 85-94
Successful infection of mammalian host by trypomastigotes of Trypanoso
ma cruzi is a complex event, involving host receptors and parasite lig
ands. Interaction of the trypomastigote stage with laminin, a componen
t of specialized extracellular matrices, as basement membranes, is stu
died in this report. Binding of I-125-laminin to trypomastigotes is sp
ecific and 2-5 x 10(3) laminin binding sites were calculated to be pre
sent on the surface of live trypomastigotes. Antilaminin antibodies we
re able to inhibit the invasion of cultured cells by trypomastigotes (
75-62%), suggesting that laminin may be involved in the adhesion of th
e parasite to host cells. By affinity chromatography, an 85-kDa glycop
rotein was isolated (laminin binding glycoprotein, LBG) from trypomast
igote lysates, but not from epimastigote lysates. It is suggested that
at least fragment E8 (but not E1') from laminin could be involved in
the reaction which is independent of the carbohydrate moieties from bo
th ligand and receptor, as suggested by glycosidase or tunicamycin tre
atments. It is also shown that LBG is an acidic component of the polym
orphic Tc-85 protein family, a trypomastigote-specific surface membran
e glycoprotein which contains several polypeptides recognized by the m
onoclonal antibody H1A10, and previously related with the invasion pro
cess of the parasite.