Fig. 1. The C-terminus of periplakin. (A) Alignment of the periplakin C-terminus with the linker sequences of other plakins. Light blue, identical amino acids; dark blue, conserved amino acids. Human periplakin (PPL) is shown from amino acid 1646; human envoplakin (EVPL) from amino acid 1675; human desmoplakin (DP) from amino acid 2454, rat plectin from amino acid 3722 and human BPAG1 from amino acid 2327 (Mahoney et al., 1998; Määttä et al., 2000). (B) Amino acid sequence of periplakin C-terminus, with residues that are most highly conserved between plakins (i.e. light or dark blue in A) shaded. The assignment of the boundary between the rod domain and linker domain is that described by Määttä et al. and DiColandrea et al. (Määttä et al., 2000; DiColandrea et al., 2000), except that the numbering has been corrected by one amino acid. (C) Periplakin C-terminal constructs tested in immunofluorescence and overlay assays. P, periplakin; R, rod domain; L, linker domain. The association of each construct with intermediate filaments (IF) was evaluated by immunofluorescence in transiently transfected COS7 cells stained with (+extraction) or without (-extraction) prior extraction and in overlay assays (overlay) with keratinocyte and COS7 cell intermediate filament preparations. +, colocalisation that was sufficiently strong to make the distribution of periplakin almost indistinguishable from intermediate filaments (strong binding in overlay assays); +/-, partial colocalisation in which the filamentous distribution of the periplakin constructs was evident without the need to overlay the intermediate filament staining pattern (weak binding in overlay assays); -, no obvious filamentous distribution; n.d., not determined.