Splicing factor that specifically promotes exon-inclusion during alternative splicing (PubMed:26876937). Interaction with YTHDC1, a RNA-binding protein that recognizes and binds N6-methyladenosine (m6A)-containing RNAs, promotes recruitment of SRSF3 to its mRNA-binding elements adjacent to m6A sites, leading to exon-inclusion during alternative splicing (PubMed:26876937). Also functions as export adapter involved in mRNA nuclear export (PubMed:11336712, PubMed:18364396, PubMed:28984244). Binds mRNA which is thought to be transferred to the NXF1-NXT1 heterodimer for export (TAP/NXF1 pathway); enhances NXF1-NXT1 RNA-binding activity (PubMed:11336712, PubMed:18364396). Involved in nuclear export of m6A-containing mRNAs via interaction with YTHDC1: interaction with YTHDC1 facilitates m6A-containing mRNA-binding to both SRSF3 and NXF1, promoting mRNA nuclear export (PubMed:28984244). RNA-binding is semi-sequence specific (PubMed:17036044). Interacts with CPSF6 (PubMed:15169763). Interacts with RBMY1A1 (PubMed:15595951). Interacts with SREK1/SFRS12 (PubMed:10757789). Interacts with NXF1 (PubMed:12667464, PubMed:17036044). Interacts with YTHDC1, leading to recruitment to RNA elements adjacent to m6A sites (PubMed:26876937, PubMed:28984244). Recruited to nuclear speckles following interaction with YTHDC1. Phosphorylated by CLK1, CLK2, CLK3 and CLK4. Extensively phosphorylated on serine residues in the RS domain. Belongs to the splicing factor SR family.