Enables protein tyrosine kinase activity. Involved in several processes, including mammary gland development; nervous system development; and positive regulation of nitrogen compound metabolic process. Acts upstream of or within several processes, including cellular response to epidermal growth factor stimulus; peptidyl-tyrosine autophosphorylation; and regulation of apoptotic process. Located in GABA-ergic synapse and glutamatergic synapse. Is integral component of postsynaptic density membrane. Is integral component of presynaptic membrane. Is expressed in several structures, including brain; early conceptus; embryo ectoderm; heart; and mammary gland primordium. Human ortholog(s) of this gene implicated in amyotrophic lateral sclerosis type 19; colorectal cancer; esophagus squamous cell carcinoma; hepatocellular carcinoma; and lung adenocarcinoma. Orthologous to human ERBB4 (erb-b2 receptor tyrosine kinase 4). [provided by Alliance of Genome Resources, Apr 2022]