(A) SDS-PAGE analysis of P4 virions (lane 1), P4 procapsids (lane 2), P2 virions (lane3) and P2 procapsids (lane 4) after transfer to nitrocellulose and staining with colloidal gold. M, marker; sizes (kDa) indicated. (B) Western blot of P2 virion proteins separated by SDS-PAGE using a rabbit polyclonal anti-gpO antibody (Marvik et al, 1994), identifying the 17 kDa band as O*. Note that the protein markers used in (A) and (B) are different, giving rise to a discrepancy in the apparent MW of O*.