The profiles of the PV IgGs absorbed by recombinant Dsg 1 and Dsg 3 baculoproteins. Western blots of protein extracts of normal human keratinocytes resolved by 7.5% SDS-PAGE and stained with PV3 IgG affinity-purified on rDsg3-His (lane 1), and that of Dsg3^null keratinocytes stained with PV3 IgG affinity purified on rDsg3-Ig-His (lane 5), rDsg1-Ig-His (lane 4) or on the Fc IgG column (lane 9). Binding of PV3 IgGs to the immunoblotting membranes was visualized using secondary, HRP-conjugated goat anti-human IgG antibodies. Lane 6 shows a single protein band with apparent M_r of 190 kDa among SDS-PAGE–resolved Dsg 3–positive keratinocyte proteins from BALB/c mouse. This band was visualized by the PV3 IgG that was eluted from the 190-kDa area of the Western blot of Dsg3^null keratinocyte proteins stained with the PV3 IgG adsorbed on rDsg3-Ig-His. Note: Only a 190-kDa but not 130- or 160-kDa band or any other keratinocyte protein was visualized, indicating that the antibody targeting the 190-kDa protein is a unique one, as it does not recognize the 130-kDa Dsg 3 or 160-kDa Dsg 1. Lanes 2, 3, and 7 are the negative controls omitting primary antibody. The Dsg3^null keratinocyte protein extract in lane 8 was blotted with normal human IgG-affinity purified on rDsg3-Ig-His. The lack of multiple bands in lane 8 as well as complete absence of specific staining in lanes 3 and 7 indicate that there were no nonspecific cross reactivities of human or goat IgGs with murine epidermal proteins. The positions of relative molecular mass markers run in parallel lanes of each blot are shown to the left of the respective blot. The apparent relative molecular mass of keratinocyte protein bands visualized due to PV antibody binding is shown to the right of lanes 2 and 5 in the columns designated M_r.