Activation of a nuclear Cdc2-related kinase within a mitogen-activated protein kinase-like TDY motif by autophosphorylation and cyclin-dependent protein kinase-activating kinase.
Male germ cell-associated kinase (MAK) and intestinal cell kinase (ICK) are nuclear Cdc2-related kinases with nearly identical N-terminal catalytic domains and more divergent C-terminal noncatalytic domains. The catalytic domain is also related to mitogen-activated protein kinases (MAPKs) and contains a corresponding TDY motif. Nuclear localization of ICK requires subdomain XI and interactions of the conserved Arg-272, but not kinase activity or, surprisingly, any of the noncatalytic domain. Further, nuclear localization of ICK is required for its activation. ICK is activated by dual phosphorylation of the TDY motif. Phosphorylation of Tyr-159 in the TDY motif requires ICK autokinase activity but confers only basal kinase activity. Full activation requires additional phosphorylation of Thr-157 in the TDY motif. Coexpression of ICK with constitutively active MEK1 or MEK5 fails to increase ICK phosphorylation or activity, suggesting that MEKs are not involved. ICK and MAK are related to Ime2p in budding yeast, and cyclin-dependent protein kinase-activating kinase Cak1p has been placed genetically upstream of Ime2p. Recombinant Cak1p phosphorylates Thr-157 in the TDY motif of recombinant ICK and activates its activity in vitro. Coexpression of ICK with wild-type CAK1 but not kinase-inactive CAK1 in cells also increases ICK phosphorylation and activity. Our studies establish ICK as the prototype for a new group of MAPK-like kinases requiring dual phosphorylation at TDY motifs.
Fu
Zheng
Z
Department of Pharmacology and Internal Medicine, University of Virginia School, 1300 Jefferson Park Avenue, Charlottesville, Virginia 22908-0735, USA.
Schroeder
Melanie J
MJ
Shabanowitz
Jeffrey
J
Kaldis
Philipp
P
Togawa
Kasumi
K
Rustgi
Anil K
AK
Hunt
Donald F
DF
Sturgill
Thomas W
TW
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D042846:CDC2-CDC28 Kinases / Q000235:genetics / Q000378:metabolism; D020134:Catalytic Domain; D002467:Cell Nucleus / Q000737:chemistry / Q000201:enzymology*; D002478:Cells, Cultured; D018844:Cyclin-Dependent Kinases / Q000502:physiology*; D004789:Enzyme Activation; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D051381:Rats; D000095043:Cyclin-Dependent Kinase-Activating Kinase
C097276:CILK1 protein, human; D017346:Protein Serine-Threonine Kinases; D042846:CDC2-CDC28 Kinases; D018844:Cyclin-Dependent Kinases; D000095043:Cyclin-Dependent Kinase-Activating Kinase