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). Required for convergent extension cell movements during gastrulation, acting with yes via rhoa. May be required for epiboly to occur, possibly through its effects in calcium signaling. 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 (By similarity). Relatively inactive in the unfertilized oocyte, undergoes rapid activation immediately following fertilization. Total activity increases progressively during later development and remains elevated during sphere and epiboly stage. Transiently expressed in the nucleus at mid-blastula stage (3.3 hpf) in a large subset of cells. Nuclear localization is not observed from late blastula stage onward. Widely expressed. Expressed in the pre-gastrula embryo (at protein level). Belongs to the protein kinase superfamily. Tyr protein kinase family. SRC subfamily.