Inefficient transition from commitment to pre-spliceosome complex assembly on FOXP3 introns is dependent on DDX39B levels. (A) Comparison of commitment and pre-spliceosome complex assembly on FOXP3 intron wt and FOXP3 intron pU. Dark gray boxes represent 5′ and 3′ exons that are intercepted by an intron (light gray) with a C-rich (C) or U-rich (U) py tract. (Key: U1 snRNP = blue circle and RNA structure, SF1 = green circle, RRM1 and RRM2 of U2AF2 = orange circles, U2AF1 = yellow circle, U2 snRNP = purple circle and RNA structure, DDX39B = red star; created with BioRender.) (B) Representative graph depicting the dependency of FOXP3 intron wt compared to FOXP3 intron pU on DDX39B levels to transition from CC to pre-spliceosome (A) complex. Normal expression of DDX39B is represented by ^, and decreased expression (∼50%) of DDX39B is represented by * (created with BioRender).
