摘要：

The chapter discusses the structure of protein kinase catalytic domains, and the classification of protein kinases according to the sequences of those domains. These enzymes use the gamma phosphate of ATP to generate phosphate monoesters utilizing protein alcohol groups, (on serine and threonine) and/or protein phenolic groups (on tyrosine) as phosphate group acceptors. They are related by virtue of their homologous "kinase domains" (also known as "catalytic domains") which consist of 250–300 amino acid residues. In addition to mammals and other vertebrates, eukaryotic protein kinase superfamily members have been identified and characterized from a wide range of other animal phyla, plants, fungi, and microorganisms. Hence, the protein kinase progenitor gene can be traced back to a time prior to the evolutionary separation of the major eukaryotic kingdoms. In the future, it may be possible to model a three-dimensional structure of a novel protein kinase catalytic domain with sufficient accuracy to be able to predict the preferred primary sequence surrounding the hydroxyamino acid it phosphorylates, which in turn will allow one to predict what proteins might be its substrates from the increasingly complete database of protein sequences.

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