Developmentally regulated, phospholipase C-mediated release of the major surface glycoprotein of amastigotes of Trypanosoma cruzi.
The surface of amastigotes of Trypanosoma cruzi is covered by Ssp-4, a major stage-specific glycoprotein. Ssp-4 is anchored to the cell membrane by GPI. It can be metabolically labeled with [3H]myristic acid, and is converted into a hydrophilic form by treatment with the glycan-specific phospholipase C of T. brucei, or after lysis of the parasites in non-ionic detergents. The hydrophilic form of Ssp-4 is recognized by antibodies to the cross-reactive determinant of the variant surface glycoprotein of African trypanosomes. Ssp-4 is progressively shed during the intra- or extracellular development of amastigotes preceding their transformation into epi- and trypomastigotes. We show here that T. cruzi contains a phospholipase C and that most shed Ssp-4 is hydrophilic, does not contain myristic acid, and reacts with anti-CRD. These observations provide strong evidence that phospholipase C mediates the release of this glycosyl-phosphatidylinositol-anchored protein under physiological conditions, as the parasite undergoes differentiation.
Andrews
N W
NW
Department of Pathology, New York University Medical Center 10016.
Robbins
E S
ES
Ley
V
V
Hong
K S
KS
Nussenzweig
V
V
D000818:Animals; D000954:Antigens, Surface / Q000302:isolation & purification; D002454:Cell Differentiation; D002462:Cell Membrane / Q000378:metabolism; D006031:Glycosylation; D008970:Molecular Weight; D010716:Phosphatidylinositols / Q000502:physiology; D014349:Trypanosoma cruzi / Q000201:enzymology / Q000254:growth & development* / Q000378:metabolism; D010738:Type C Phospholipases / Q000502:physiology*; D014643:Variant Surface Glycoproteins, Trypanosoma / Q000302:isolation & purification / Q000378:metabolism*
D000954:Antigens, Surface; D010716:Phosphatidylinositols; D014643:Variant Surface Glycoproteins, Trypanosoma; D010738:Type C Phospholipases