Envelope polypeptides of Friend leukemia virus: purification and structural analysis.
Roughly 10% of surface glycoproteins in the envelope of mature Friend murine leukemia virus are coupled to membrane polypeptides by disulfide bridges. The remaining 90% of these glycoproteins are associated noncovalently. However, they could also be linked to membrane polypeptides by the treatment of purified Friend murine leukemia virus with 2,2'dithiobis(m-nitropyridine). These amphiphilic heterodimer polypeptides, gp84/86, were recovered almost quantitatively in the form of aggregates, termed rosettes, when prepared by solubilization of the viral membrane with Triton X-100 and subsequent velocity sedimentation. gp69/71 and p12(E)/15(E) were purified from these protein micelles after reduction of the disulfide bonds by gel chromatography. Electron micrographs of rosettes, as well as of purified p12(E)/15(E), showed structures different from native viral knobs. Isolated gp84/86 could be reassociated and then displayed more similarity to these viral surface projections. As shown by peptide mapping, the primary structures of the glycoproteins gp69/71 are highly related as are those of the membrane polypeptides p12(E) and p15(E). Furthermore, it was shown by two-dimensional polyacrylamide gel electrophoresis and re-electrophoresis of purified gp84/86 that the larger component, gp86, was composed of gp71 associated with p15(E) and p12(E), whereas the smaller component, gp84, was formed by gp69 bound only to p12(E).
D000818:Animals; D002850:Chromatography, Gel; D004220:Disulfides / Q000494:pharmacology; D004591:Electrophoresis, Polyacrylamide Gel; D005622:Friend murine leukemia virus / Q000032:analysis*; D006023:Glycoproteins / Q000302:isolation & purification; D008565:Membrane Proteins / Q000302:isolation & purification; D051379:Mice; D010446:Peptide Fragments / Q000032:analysis; D011725:Pyridines / Q000494:pharmacology; D014764:Viral Proteins / Q000276:immunology / Q000302:isolation & purification*
D004220:Disulfides; D006023:Glycoproteins; D008565:Membrane Proteins; D010446:Peptide Fragments; D011725:Pyridines; D014764:Viral Proteins; C011801:2,2'-dithiobis(5-nitropyridine)