FIG. 3.

SCMV BPP binds to isolated SCMV capsids in vitro. Nuclear and cytoplasmic capsids were combined with ³⁵S-sBPP and subjected to rate-velocity centrifugation; the resulting gradients were fractionated, and duplicate sets of samples were subjected to SDS-PAGE (separate gels for each gradient) and Western immunoassay (a single gel and membrane containing all cytoplasmic and nuclear gradient fractions). Phosphorimages of the nuclear (A) and cytoplasmic (B) gradient fractions following SDS-PAGE are shown. The insets show a portion of the Western immunoassay after the membrane was probed to detect mCP, mCBP, and AP. B and C denote fractions containing B- and C-capsids. The B-capsid peak was split between two fractions in both gradients. The nuclear capsid preparation (3.5 ml) and the cytoplasmic capsid preparation (2.5 ml) were loaded onto the gradients; that material is in the first 7 (A) or 5 (B) fractions, labeled Load. Pel denotes the pellet. The arrow in panel B indicates the location of the SCMV BPP band. The asterisks denote proteins in the BPP translation mixture (the leftmost lane in both panels) that did not bind well to the capsids. The numbers at the bottoms of the panels and insets indicate corresponding fraction numbers.