RNA-binding protein which binds to intronic polypyrimidine tracts and mediates negative regulation of exons splicing (PubMed:10829067, PubMed:30638744). May antagonize in a tissue-specific manner the ability of NOVA1 to activate exon selection (PubMed:10829067). In addition to its function in pre-mRNA splicing, also plays a role in the regulation of translation (PubMed:11726525). Monomer. Identified in a mRNP complex, at least composed of DHX9, DDX3X, ELAVL1, HNRNPU, IGF2BP1, ILF3, PABPC1, PCBP2, PTBP2, STAU1, STAU2, SYNCRIP and YBX1. Part of a ternary complex containing KHSRP and HNRPH1 (By similarity). Interacts with NOVA1; the interaction is direct (PubMed:10829067). Interacts with NOVA2; the interaction is direct (PubMed:10829067). Mainly expressed in brain, including cerebellum, brainstem, spinal cord, and hypothalamus. Also expressed in the peripheral nervous system and neural crest derivatives, including the dorsal root and trigeminal ganglia, the cochlear spiral and intestinal ganglion cells, and the adrenal medulla. Also detected to a lower extent in testis, heart, liver, lung, skeletal muscle and thymus (at protein level). Expressed in whole brain tissues from 11.5 dpc to adulthood.