Fig 1: Enhanced CRM1/FXR interaction promotes nuclear export of FXR in apoptotic HepG2 cells. (A) Alignment of the FXR region containing predicted NES sequences from various species. Predicted NESs were indicated in boldface type. (B) Alignment of human FXR amino acids 404–450 around the predicted NESs. Predicted NESs were indicated in boldface type and the mutants were in red. (C) Mutations of FXR NESs caused its nuclear retention. (D) Mutations of FXR NESs impaired their functions in nuclear export of NLS cargo reporter. (E) Mutations of FXR NESs prevented its degradation upon apoptotic trigger. (F–H) Association between FXR and CRM1 was detected by Co-IP analysis (F), GST pull-down analysis (G) and BLI analysis (H). (I) Mutations of FXR NESs impaired the interaction between FXR and CRM1. (J) Leptomycin B, a CRM1 inhibitor, prevented nuclear export of FXR protein. (K and L) Enhanced FXR-CRM1 interaction in apoptotic HepG2 cells by Co-IP assay (K) and PLA (L). (M) CRM1 knock-down by specific siRNA transfection prevented FXR degradation stimulated by ActD/TNFa. Scale bar, 20 µm.