Analysis of lettuce necrotic yellows virus structural proteins with monoclonal antibodies and concanavalin A

Three major structural proteins of lettuce necrotic yellow virus (LNYV) were identified by discontinuous polyacrylamide gel electrophoresis (PAGE) to have Mr approximately 78,000 (G), 57,000 (N), and 19,000 (M). Unreduced G and M proteins had faster mobilities in PAGE indicating the presence of disulfide bonds. The G protein was shown to be glycosylated with a complex network of oligosaccharides containing beta-N-acetylchitobiose N-linked to asparagine residues of the protein. Up to 17 additional minor bands were also detected in silver-stained electrophoretograms. In Western immunoblots, 9 of these (Mr approximately 27,000-220,000) were recognized by a monoclonal antibody to the N protein and another 6 (Mr approximately 58,000-180,000) with a monoclonal antibody to the G protein, indicating that they were degradation products or aggregates of these two viral proteins. Two minor silver-stained bands failed to react with either of the monoclonal antibodies, but were recognized by polyclonal anti-LNYV serum and are probably the L (Mr approximately 190,000) and NS (Mr approximately 38,000) viral proteins.