The score of the branchpoint sequence is correlated to the splicing efficiency of most minor introns. RT-PCR analysis of minor introns splicing in spinal cords of control (WT6, WT7) and SMA (KO6, KO9, KO10) mice. Gene names and size (in base pairs) of the amplified products are indicated on the left. The schematic structure of the amplified products is shown on the right. The branchpoint sequence aligned with the anti-branch site of the U12 snRNA (in italics) as well as the BPS scores are shown on the right. The putative branch site adenosine is indicated in bold. (A) Minor introns containing canonical branchpoint sequences. (B) Minor introns containing suboptimal branchpoint sequences. (C) Retention index of minor introns in spinal cords of control (WT, n = 2) and SMA (SMA, n = 3) mice determined as described in the Materials and Methods section. Mean and SEM are shown. Statistical significance was calculated using the Student t-test (ns: nonsignificant; (*) P < 0.05; (**) P < 0.01). Histograms for Srpk1 are not shown because retained introns are not detectable.
