ATP + L-tyrosyl-[protein] = ADP + H(+) + O-phospho-L-tyrosyl-[protein] This protein is produced by erythroleukemia cells in chickens which have been injected with the avian leukosis virus and subsequently develop leukemia. The leukemias are induced by the insertion of retroviral promoter elements in or near the c-erbB gene, which leads to c-erbB activation. This protein is synthesized as a Gag-Env-ErbB protein. Belongs to the protein kinase superfamily. Tyr protein kinase family. EGF receptor subfamily.