Probable non-receptor tyrosine-protein kinase which plays a role in spermatid activation (spermiogenesis) in hermaphrodites. ATP + L-tyrosyl-[protein] = ADP + H(+) + O-phospho-L-tyrosyl-[protein] Localizes mainly in the cytoplasm in stage I spermatocytes and at the cell membrane in stage II spermatocytes and in spermatids. Expressed in hermaphrodite larvae but not in adult. Expressed in both male larvae and adult. Belongs to the protein kinase superfamily. Tyr protein kinase family. Fes/fps subfamily.