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 (By similarity). ATP + L-tyrosyl-[protein] = ADP + H(+) + O-phospho-L-tyrosyl-[protein] Inhibited by phosphorylation of Tyr-531 by leukocyte common antigen and activated by dephosphorylation of this site. Associates through its SH3 domain, to the p85 subunit of phosphatidylinositol 3-kinase. Belongs to the protein kinase superfamily. Tyr protein kinase family. SRC subfamily.