Definition of protein kinase
: any of a class of enzymes that catalyze the transfer of a phosphate group from ATP to one or more amino acids in the side chain of a protein resulting in a conformational change affecting protein function
First Known Use of protein kinase
Medical Definition of protein kinase
: any of a class of allosteric enzymes that possess a catalytic subunit which transfers a phosphate from ATP to one or more amino acid residues (as serine, threonine, or tyrosine) in a protein's side chain resulting in a conformational change affecting protein function, that play a role in regulating intracellular processes, and that include many which are activated by the binding of a second messenger (as cyclic AMP)
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