Plays a role in preventing exon skipping, ensuring the accuracy of splicing and regulating alternative splicing (PubMed:28785060). Interacts with other spliceosomal components, via the RS domains, to form a bridge between the 5'- and 3'-splice site binding components, U1 snRNP and U2AF. Can stimulate binding of U1 snRNP to a 5'-splice site-containing pre-mRNA.

Binds to purine-rich RNA sequences, either the octamer, 5'-RGAAGAAC-3' (r=A or G) or the decamers, AGGACAGAGC/AGGACGAAGC. Binds preferentially to the 5'-CGAGGCG-3' motif in vitro. Three copies of the octamer constitute a powerful splicing enhancer in vitro, the ASF/SF2 splicing enhancer (ASE) which can specifically activate ASE-dependent splicing (By similarity).

Specifically regulates alternative splicing of cardiac isoforms of CAMK2D, LDB3/CYPHER and TNNT2/CTNT during heart remodeling at the juvenile to adult transition. The inappropriate accumulation of a neonatal and neuronal isoform of CAMKD2 in the adult heart results in aberrant calcium handling and defective excitation-contraction coupling in cardiomyocytes. May function as export adapter involved in mRNA nuclear export through the TAP/NXF1 pathway (PubMed:15652482)

Consists of two polypeptides of p32 and p33. Identified in the spliceosome C complex. Component of a ribonucleoprotein complex containing mRNAs and RNA-binding proteins including DDX5, HNRNPH2 and SRSF1 as well as splicing regulator ARVCF (By similarity).

In vitro, self-associates and binds SRSF2, SNRNP70 and U2AF1 but not U2AF2. Binds SREK1/SFRS12. Interacts with SAFB/SAFB1.

Interacts with PSIP1/LEDGF. Interacts with RSRC1 (via Arg/Ser-rich domain). Interacts with ZRSR2/U2AF1-RS2.

Interacts with CCDC55 (via C-terminus). Interacts with SRPK1 and a sliding docking interaction is essential for its sequential and processive phosphorylation by SRPK1. Interacts with NXF1.

Interacts with CCNL1, CCNL2 and CDK11B. Interacts with RRP1B. Interacts (when phosphorylated in its RS domain) with TNPO3; promoting nuclear import.

Interacts with ILDR1 (via C-terminus) and ILDR2 (PubMed:28785060)

Expressed in inner ear

The RRM 2 domain plays an important role in governing both the binding mode and the phosphorylation mechanism of the RS domain by SRPK1. RS domain and RRM 2 are uniquely positioned to initiate a highly directional (C-terminus to N-terminus) phosphorylation reaction in which the RS domain slides through an extended electronegative channel separating the docking groove of SRPK1 and the active site. RRM 2 binds toward the periphery of the active site and guides the directional phosphorylation mechanism.

Both the RS domain and an RRM domain are required for nucleocytoplasmic shuttling (By similarity)