Fig. 6

SPRE activity depends on the protein-coding sequence. a Schematic representation of codon-optimized (CO) syncytin-2 and chimera syncytin-2 expression plasmids. The wild-type (WT) syncytin-2 in pFRDE1 indicated in Fig. 1e was replaced by CO-syncytin-2. b Fusion-dependent luciferase assay in WT-syncytin-2, CO-syncytin-2, Chimera-A, and Chimera-B, with wild-type SPRE (SPRE-WT) or mutated SPRE the same as Fig. 1c (SPRE-Mut). Each value was normalized by WT-syncytin-2 with SPRE-WT, individual data points are indicated as points, and medians are indicated as bars