Activation loop

Kinase Glossary: Activation Loop

The activation loop is a region in all ePK kinases between the DFG and APE motifs. Most kinases are activated by phosphorylation of specific residues in the activation loop, which then counteract the positive charge of the arginine in the catalytic loop HRD motif. Tyrosine kinases usually have one or two tyrosines in the loop, MAPK kinases have a T[DE]Y motif, which is phosphorylated on both T and Y, and most other kinases have a threonine within the loop.