Fig. 4. Overlay assays of the interaction of periplakin constructs with intermediate filaments. (A) Autoradiography of [³⁵S]-methionine-labeled in vitro translated probes. Mobility of molecular mass standards of 200, 150, 100, 75, 50, 37 and 25 kDa are indicated. (B) Binding of [³⁵S]-methionine-labeled periplakin recombinant proteins to unlabelled intermediate filaments (IF) extracted from cultured epidermal keratinocytes and COS7 cells. CBB: Coomassie Brilliant Blue staining of intermediate filament preparations prior to transfer to nitrocellulose. Probes are described in Figs 1 and 5 or as follows. P-R, periplakin rod domain; pCI-neo, empty vector control; DP-C, desmoplakin construct with intact C-terminus [DPNwt (Stappenbeck and Green, 1992)]; K5/K14, keratin 5 and 14.