Fig. 6.

Mutations in the DHX15-SUGP1 G-patch fusion protein abolish the rescue effect. (A, Upper) Schematic representation of plasmid constructs (1 to 5) expressing HA-tagged DHX15-SUGP1 (aa 543–645) fusion protein and its mutants P449E, P533E, R222G, and D260N, respectively. (Lower) Vec or expression plasmid for HA-tagged SF3B1 (WT or K700E) was co-transfected with Vec or one of the five constructs (as indicated) in HEK293T cells, followed by ³²P RT-PCR of the cryptic 3′ss (open arrowheads) and canonical 3′ss (solid arrowheads) of the indicated genes. (B) Quantification of the ³²P RT-PCR products in (A). PSI of the cryptic 3′ss of the indicated genes is shown. Error bars represent SDs of the means (n = 3; three independent experiments). *P < 0.05, **P < 0.01, ***P < 0.001, and ****P < 0.0001 (unpaired, two-tailed, and unequal variance t test). (C) Western blotting of protein extracts from HEK293T cells in (A).