title: Insights into the regulation of eukaryotic elongation factor 2 kinase and the interplay between its domains.
abstract: eEF2K (eukaryotic elongation factor 2 kinase) is a Ca2+/CaM (calmodulin)-dependent protein kinase which regulates the translation elongation machinery. eEF2K belongs to the small group of so-called 'α-kinases' which are distinct from the main eukaryotic protein kinase superfamily. In addition to the α-kinase catalytic domain, other domains have been identified in eEF2K: a CaM-binding region, N-terminal to the kinase domain; a C-terminal region containing several predicted α-helices (resembling SEL1 domains); and a probably rather unstructured 'linker' region connecting them. In the present paper, we demonstrate: (i) that several highly conserved residues, implicated in binding ATP or metal ions, are critical for eEF2K activity; (ii) that Ca2+/CaM enhance the ability of eEF2K to bind to ATP, providing the first insight into the allosteric control of eEF2K; (iii) that the CaM-binding/α-kinase domain of eEF2K itself possesses autokinase activity, but is unable to phosphorylate substrates in trans; (iv) that phosphorylation of these substrates requires the SEL1-like domains of eEF2K; and (v) that highly conserved residues in the C-terminal tip of eEF2K are essential for the phosphorylation of eEF2, but not a peptide substrate. On the basis of these findings, we propose a model for the functional organization and control of eEF2K.
authors: Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, BC, Canada.
authors: Craig R
authors: CR
authors: Pigott
authors: Halina
authors: H
authors: Mikolajek
authors: Claire E
authors: CE
authors: Moore
authors: Stephen J
authors: SJ
authors: Finn
authors: Curtis W
authors: CW
authors: Phippen
authors: Jörn M
authors: JM
authors: Werner
authors: Christopher G
authors: CG
authors: Proud
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D020134:Catalytic Domain / Q000187:drug effects; D054736:Elongation Factor 2 Kinase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D019906:Nuclear Magnetic Resonance, Biomolecular; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D015032:Zinc / Q000737:chemistry
chemical_list: C517689:EEF2K protein, human; D054736:Elongation Factor 2 Kinase; D015032:Zinc