The complete pathway for catalytic activation of the mitogen-activated protein kinase, ERK2.
The mitogen-activated protein (MAP) kinase ERK2 is an essential signal transduction molecule that mediates extracellular signaling by all polypeptide growth factors. Full activation of ERK2 requires phosphorylation at both a threonine residue (Thr(183)) conserved in most protein kinases as well as a tyrosine residue (Tyr(185)) unique to members of the mitogen-activated protein kinase family. We have characterized the kinetic role of phosphorylation at each site with respect to the overall activation mechanism, providing a complete picture of the reaction steps involved. Phosphorylation at Tyr(185) serves to configure the ATP binding site, while phosphorylation at both residues is required to stabilize binding of the protein substrate, myelin basic protein. Similar control mechanisms are employed to stabilize ATP and myelin basic protein in the phosphoryl group transfer reaction, accounting for the enormous increase in turnover rate. The mechanism of ERK2 activation is kinetically similar to that of the cell cycle control protein, cdk2/cyclinA. Phosphorylation of Tyr(185) in ERK2 and association of cyclinA with cdk2 both serve to stabilize ATP binding. Subsequent phosphorylation of both enzymes on threonine serves to stabilize binding of the phosphoacceptor substrate.
Prowse
C N
CN
Biomedical Sciences Graduate Program, School of Medicine, University of California, San Diego, California 92093, USA.
Deal
M S
MS
Lew
J
J
D000255:Adenosine Triphosphate / Q000378:metabolism; D001665:Binding Sites; D042846:CDC2-CDC28 Kinases; D002384:Catalysis; D019925:Cyclin A / Q000378:metabolism; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases / Q000378:metabolism; D004789:Enzyme Activation; D007700:Kinetics; D019950:Mitogen-Activated Protein Kinase 1 / Q000235:genetics / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D013912:Threonine / Q000378:metabolism; D014443:Tyrosine / Q000378:metabolism
D019925:Cyclin A; D013912:Threonine; D014443:Tyrosine; D000255:Adenosine Triphosphate; D017346:Protein Serine-Threonine Kinases; D042846:CDC2-CDC28 Kinases; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases; D019950:Mitogen-Activated Protein Kinase 1