A chaperone-dependent GSK3beta transitional intermediate mediates activation-loop autophosphorylation.
Glycogen synthase kinase 3 (GSK3), a key component of the insulin and wnt signaling pathways, is unusual, as it is constitutively active and is inhibited in response to upstream signals. Kinase activity is thought to be increased by intramolecular phosphorylation of a tyrosine in the activation loop (Y216 in GSK3beta), whose timing and mechanism is undefined. We show that GSK3beta autophosphorylates Y216 as a chaperone-dependent transitional intermediate possessing intramolecular tyrosine kinase activity and displaying different sensitivity to small-molecule inhibitors compared to mature GSK3beta. After autophosphorylation, mature GSK3beta is then an intermolecular serine/threonine kinase no longer requiring a chaperone. This shows that autoactivating kinases have adopted different molecular mechanisms for autophosphorylation; and for kinases such as GSK3, inhibitors that affect only the transitional intermediate would be missed in conventional drug screens.
Lochhead
Pamela A
PA
The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Glasgow, G61 1BD. p.lochhead@beatson.gla.ac.uk <p.lochhead@beatson.gla.ac.uk>
Kinstrie
Ross
R
Sibbet
Gary
G
Rawjee
Teeara
T
Morrice
Nick
N
Cleghon
Vaughn
V
D000818:Animals; D002460:Cell Line; D004789:Enzyme Activation / Q000187:drug effects / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005786:Gene Expression Regulation; D038362:Glycogen Synthase Kinase 3 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D018841:HSP90 Heat-Shock Proteins / Q000378:metabolism*; D006801:Humans; D018832:Molecular Chaperones / Q000378:metabolism*; D010766:Phosphorylation; D017510:Protein Folding; D011505:Protein-Tyrosine Kinases / Q000502:physiology*; D015398:Signal Transduction; D014443:Tyrosine / Q000235:genetics / Q000378:metabolism
D004791:Enzyme Inhibitors; D018841:HSP90 Heat-Shock Proteins; D018832:Molecular Chaperones; D014443:Tyrosine; D011505:Protein-Tyrosine Kinases; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; D038362:Glycogen Synthase Kinase 3