While the catalytic domain of these kinases is highly conserved, the sequence variation that is observed in the kinome (the subset of genes in the genome that encode kinases) provides for recognition of distinct substrates.
Dok je katalitički domen ovih kinaza veoma konzerviran, niz varijacija koje su primećene u kinomu (podskupu gena u genomu koji kodiraju kinaze) omogućava prepoznavanje različitih supstrata.