Tyrosine kinases are one subfamily of a a large superfamily of proteins. These proteins are all responsible for catalyising the reaction phosphorylation. Phosphorylation is the transfer of a phosphate group from a donor to a recipient and in the case of of tyrosine kinases, the recipient is the amino acid tyrosine. In this way tyrosine kinases are highly associated with signalling pathways and are essential for many cellular function such as growth, apoptosis and metabolism.
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Did you know that 70% of known oncogenes and proto-oncogenes are tyrosine kinases.