Required for embryogenesis and germline development in both adult hermaphrodites and males. SR-protein kinase (SRPK) that binds directly to and phosphorylates RS domains (By similarity). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Belongs to the protein kinase superfamily. Ser/Thr protein kinase family.