ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Testis specific. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family. Ser-854 is present instead of the conserved Asp which is expected to be an active site residue.