FIG. 5.

Interaction of ³⁵S-labeled M protein with purified nucleocapsids. (A) Scheme of the assay developed to study the binding of the M protein to a nucleocapsid based on protein G-Sepharose beads coated with MAb 3D.C10 specific for the N protein (αN MAb) and purified nucleocapsids (top). Wild-type M protein and luciferase were transcribed in vitro and labeled with [³⁵S]methionine/cysteine. M protein or luciferase was incubated with the nucleocapsid complex, and the bound proteins were analyzed by SDS-PAGE and fluorography (lower part of panel A). + and −, presence and absence of the indicated component in the assay. (B) Inhibition of binding of the M protein to a nucleocapsid by increasing concentrations of unlabeled proteins. The bound M protein was analyzed by SDS-PAGE and fluorography. (C) Effect of nucleocapsid immunocomplexes' incubation with RNase (60 μg/ml for 60 min at 37°C) on recognition of the M protein in the assay described for panel A.