Tyrosine-protein kinase implicated in the control of cell growth. Plays a role in the regulation of intracellular calcium levels. Required in brain development and mature brain function with important roles in the regulation of axon growth, axon guidance, and neurite extension. Role in CNTN1-mediated signaling (By similarity). ATP + L-tyrosyl-[protein] = ADP + H(+) + O-phospho-L-tyrosyl-[protein] Inhibited by phosphorylation of Tyr-538 by leukocyte common antigen and activated by dephosphorylation of this site. Belongs to the protein kinase superfamily. Tyr protein kinase family. SRC subfamily.