Fig. 4. Periplakin binds to the intermediate filament vimentin. (A) Periplakin interacts with vimentin. COS-7 cells were transiently transfected with myc-tagged c-ppl and co-immunoprecipitations were performed in PKB buffer using anti-myc and anti-vimentin antibodies. Samples were analysed by western blotting using either the anti-myc (anti-myc 9E10) or anti-vimentin (anti-vimentin, Oncogene Science) antibody. (B) Periplakin colocalises with vimentin. Rat-1 cells were transiently transfected with myc-tagged c-ppl and immunostained for myc-c-ppl and endogenous vimentin. Bars, 10 µm. (C) Myc-c-ppl is present in vimentin fractions. A14 cells were transiently transfected with myc-tagged c-ppl and fractionated using a KI-protocol. The fractions were immunostained for vimentin, actin and myc-c-ppl. Fraction 1, total; 2, cytosolic and membrane; 3, actin; and 4, vimentin. (D) Comparison of C-terminal deletion mutants and their binding to PKB and vimentin. The C-terminal part of periplakin is shown. Binding was determined by co-immunoprecipitation and yeast two-hybrid analysis.