Interaction of Karα4 NLS major binding site with CHIKV CP. (A) Molecular model of Karα4. The residues highlighted in orange are conserved residues of Karα4 forming the surface of the major and the minor NLS recognition site. N- and C-terminus are indicated by N and C, respectively. (B) CP binds to the Karα4 major binding site. HEK293 cells after transfection with FLAG-tagged pCAGGSKarα4, Karα4Δ259, or both were lysed and incubated with purified CHIKV CP followed by Ni-NTA pull-down. The upper panel (lanes 1 to 6) was probed with anti-FLAG and the corresponding lanes 4 to 6 in the lower panel with an anti-His antibody.