Identification of regions on Fsp27 responsible for its LDCS enrichment and activity. (A and B) Representative images (A) and a schematic diagram (B) showing the localization of Fsp27-GFP truncations and their activity to enlarge LDs in 3T3-L1 preadipocytes. Insets show enlargements of the boxed regions. CIDE-N and CIDE-C respectively refer to the evolutionary conserved domains at N- and C-terminal regions of CIDE family proteins. Bars, 5 µm. (C) Sequence alignment of aa 181–191 of Fsp27 with the corresponding region on Cidea and Cideb. Boxes highlight the conserved basic residues. KKRA represents substitutions of all three basic residues of Fsp27 with alanine. (D and E) LD number (D) and size distribution (E) in cells expressing Fsp27-GFP or its truncations. NS, no significant difference. **, P < 0.01; ***, P < 0.001. Data were collected from 30 GFP-positive cells in each group. Error bars represent SEM.