Tyrosine kinase

A Tyrosine Kinase is an enzyme which catalyzes the transfer of a phosphate group from ATP (Adenosine Triphosphate) to the amino acid tyrosine. This process is known as tyrosine phosphorylation. Tyrosines with a phosphate group are called phosphotyrosines. Tyrosines are present in several cellular proteins which are involved in signaling pathways (this includes tyrosine kinases themselves). These types of signaling pathways predominantly control cell growth, differentiation and migration, as well as metabolism and communication between cells. Tyrosine phosphorylation is a highly controlled process under normal conditions. In non-dividing cells, tyrosine phosphorylation is at a very low level. In dividing cells, it is abundant. An extraordinarily high amount of tyrosine phosphorylation is also seen in cancer cells.