More About Kinases (Dual Specificity)
Protein kinases fall into three broad classes, characterised with respect to substrate specificity: Serine/threonine-protein kinases, Tyrosine-protein kinases, and Dual specificity protein kinases (e.g. MEK - phosphorylates both Thr and Tyr on target proteins)[1].
[1] S.K. Hanks et al. The protein kinase family: conserved features and deduced phylogeny of the catalytic domains. Science. 1988, 241, 42-52.