Analysis of the ferritoid–ferritin interaction and nuclear transport in COS-1 cells. A: COS-1 cells co-transfected with ferritin and either a wild-type ferritoid construct (NLS+) or a ferritoid construct lacking the NLS (NLS−), and analyzed by immunoprecipitation with ferritin antibody followed by Western blot for ferritoid (IP:FTN/WB:FTD). B: Schematic of a wild-type ferritoid construct (FTD-wt) and a full-length ferritoid construct containing point mutations in C-terminal serine residues 186, 208, 212, 240 (FTD-Pmut). C: Immunofluorescence micrographs of COS-1 cells co-transfected with a full-length myc-tagged ferritin construct and the V5-tagged construct for either wild-type ferritoid (FTD-wt) or ferritoid containing point mutations (FTD-Pmut) from (B). Ferritoid is shown in green, ferritin in red, and a merged image is shown to highlight subcellular distribution of the proteins. Scale bar in top right panel = 50 μm.