Involved in pre-mRNA splicing as component of the spliceosome. Intron-binding spliceosomal protein required to link pre-mRNA splicing and snoRNP (small nucleolar ribonucleoprotein) biogenesis. Plays a key role in position-dependent assembly of intron-encoded box C/D small snoRNP, splicing being required for snoRNP assembly. May act by helping the folding of the snoRNA sequence. Binds to intron of pre-mRNAs in a sequence-independent manner, contacting the region between snoRNA and the branchpoint of introns (40 nucleotides upstream of the branchpoint) during the late stages of splicing. Has ATP-dependent RNA helicase activity and can unwind double-stranded RNA molecules with a 3' overhang (in vitro). ATP + H2O = ADP + H(+) + phosphate Identified in the spliceosome C complex. Component of the XAB2 complex, a multimeric protein complex composed of XAB2, PRPF19, AQR, ZNF830, ISY1, and PPIE. Identified in a pentameric intron-binding (IB) complex composed of AQR, XAB2, ISY1, ZNF830 and PPIE that is incorporated into the spliceosome as a preassembled complex. The IB complex does not contain PRPF19. Within the spliceosome, interacts with SNRPA1, SF3B1, SF3B3, SF3A1 and SF3A2. Localizes to speckle-like regions of the nucleoplasm. First detected at 8.5 dpc, when neural crest cells are visible at the lateral ridges of the neural plate. During embryogenesis, it is expressed in mesoderm, in the neural crest (and its target tissues) and in neuroepithelium. By retinoic acid (RA). Contains an N-terminal domain with structural similarity to ARM repeat regions; this domain functions as scaffold for protein-protein interactions, but is not required for RNA binding or for ATP-dependent RNA helicase activity. Belongs to the CWF11 family. Extended N-terminus.