Splicing factor involved in constitutive and/or alternative splicing. Regulates the splicing of its own pre-mRNA and the alternative splicing of RS30, RS31 and RS34. Associates the cyclin-dependent kinase G1 (CDKG1) with the spliceosome and recruits it to U1 snRNP to facilitate splicing. Component of the spliceosome. Interacts with SNRNP35, CDKG1, cyp59, SR33, SR34, RSZ21, RSZ22, SCL28, SCL30, SCL30A, SCL33 and SC35 (PubMed:10593939, PubMed:12176998, PubMed:15987817, PubMed:16497658, PubMed:23404887). Interacts with MOS14 (PubMed:21738492). Expressed in roots, flowers, anthers, pollen, ovules, style and developing seeds. Not detected in stems or leaves. Extensively phosphorylated on serine residues in the RS domain. The splicing pattern of the pre-mRNA is regulated in a tissue-specific manner and by development, and changes in response to various types of abiotic stresses (PubMed:17319848), but is not affected by the light/dark regimes (PubMed:24763593). Belongs to the splicing factor SR family. RS2Z subfamily. Truncated C-terminus.