Avian endogenous retroviral envelope glycoprotein is assembled in two structural complexes of gp85 and gp37 subunits

Abstract

Experiments were undertaken to determine the subunit structure of endogenous retroviral envelope glycoprotein present on Rous-associated virus-O (RAV-O) or expressed by 15I 5 × 7 2 fibroblasts and plasma cells. As analyzed under nonreducing conditions, the RAV-O-associated and 15I 5 × 7 2 cell-associated envelope glycoprotein comprised two components, designated VGP1 and VGP2, with approximate molecular weights of 200,000 and 100,000, respectively. By contrast, the envelope glycoprotein of exogenous strains of virus comprised predominantly, if not exclusively, VGP2. Our interpretation of the structural data is that VGP1 and VGP2 represent, respectively, a disulfide-linked tetramer and dimer of equimolar gp85 and gp37 subunits.