Dual specificity kinase acting on both serine/threonine and tyrosine-containing substrates. Phosphorylates serine- and arginine-rich (SR) proteins of the spliceosomal complex. May be a constituent of a network of regulatory mechanisms that enable SR proteins to control RNA splicing and can cause redistribution of SR proteins from speckles to a diffuse nucleoplasmic distribution. Phosphorylates SRSF1 and SRSF3. Regulates the alternative splicing of tissue factor (F3) pre-mRNA in endothelial cells. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] ATP + L-tyrosyl-[protein] = ADP + H(+) + O-phospho-L-tyrosyl-[protein] Leucettine L41 inhibits its kinase activity and affects the regulation of alternative splicing mediated by phosphorylation of SR proteins. Present at high levels in testis and ovary. In testis, expression is restricted to elongated, maturing spermatozoa. Also present in spleen, brain, lung and liver (at protein level). Autophosphorylates on all three types of residues. Belongs to the protein kinase superfamily. CMGC Ser/Thr protein kinase family. Lammer subfamily. Truncated N-terminus. Truncated N-terminus. Truncated N-terminus. Truncated N-terminus. Truncated N-terminus. Truncated N-terminus.