May play an essential role in neuronal pathway recognition and ventral muscle attachment site selection. ATP + L-tyrosyl-[protein] = ADP + H(+) + O-phospho-L-tyrosyl-[protein] Expressed in dynamic domains in the embryonic epidermis, many of which border on sites of epithelial invagination into the embryo interior, including ventral furrow, cephalic furrow, fore- and hindgut, optic lobe and tracheal pits. Later in embryogenesis, expression is seen in imaginal tissues. Expressed both maternally and zygotically from embryos to adults. High expression is seen in embryos, pupae and adults (highest in early pupae) and low expression in larvae. Belongs to the protein kinase superfamily. Tyr protein kinase family.