Fig. 3. Mapping of the interacting sites between N-terminal plectin 1 (PleN1) fragments and full-length β-synemin by in vitro pull-down assay. (A) Schematic representations of the domain structures of full-length β-synemin and GST-fused recombinant β-synemin fragments used in the pull-down assay. The in vitro PleN1-binding phenotypes of mutant β-synemin fragments are summarized as + (strong binding) or ± (weak binding). GST-fused β-synemin fragments were incubated with Myc-tagged PleN1 and immunoprecipitated by anti-Myc antibody and protein L-agarose. These immunoprecipitates were subjected to immunoblotting with detection by anti-GST antibody. Each lane contained equivalent amounts of the immunoprecipitate, as represented by immunoblots of PleN1. (B) Domain structures of PleN1 and Myc-tagged recombinant plectin fragments, together with a summary of in vitro binding ability of plectin fragments to β-synemin tail fragments (Tail N1). Plectin fragments were incubated with GST-fused Tail N1 and pulled down using glutathione beads, followed by immunoblotting with anti-Myc antibody. Each lane contained equivalent amounts of the immunoprecipitate, as represented by immunoblots of Tail N1.