Pre-mRNA splicing occurs in 2 sequential transesterification steps. The protein encoded by this gene is a component of both U2- and U12-dependent spliceosomes, and found to be essential for the catalytic step II in pre-mRNA splicing process. It contains several WD repeats, which function in protein-protein interactions. This protein has a sequence similarity to yeast Prp8 protein. This gene is a candidate gene for autosomal dominant retinitis pigmentosa. [provided by RefSeq, Jul 2008].