GENERATION OF A WATER-SOLUBLE OLIGOMERIC ECTODOMAIN OF THE ROUS-SARCOMA VIRUS ENVELOPE GLYCOPROTEIN

Sequences encoding the transmembrane domain of the Rous sarcoma virus envelope (Env) glycoprotein were deleted and replaced with sequences that signal addition of a glycosyl phosphatidylinositol (GPI) membrane anchor. Stable NIH 3T3 cell lines expressing either the wild-type transmembrane-anchored Env or the Env chimera with a GPI tail were established. The GPI-anchored envelope glycoprotein is expressed, oligomerized, and transported to the cell surface in a manner identical to that of its wild-type transmembrane-anchored counterpart. The GPI-linked protein is quantitatively removed from the cell surface by treatment with phosphatidylinositol phospholipase C. The phosphatidylinositol phospholipase C-released, water-soluble Env glycoprotein ectodomain retains the wild-type oligomeric structure and provides a useful tool for studying the subgroup-specific binding and fusion activities of a prototypic retroviral Env glycoprotein.