Crystal structure of human ERK2 complexed with a pyrazolo[3,4-c]pyridazine derivative

A series of pyrazolopyridazine compounds were briefly investigated as ERK2 inhibitors. The crystal structure of ERK2 complexed with an allyl derivative was determined. The compound induces structural change including movement of the glycine-rich loop and peptide flip between Met108-Glu109. As a result, the newly formed subsite can recognize small hydrophobic substituents but not hydrophilic ones.