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== Function == | == Function == | ||
[[http://www.uniprot.org/uniprot/MHCKA_DICDI MHCKA_DICDI]] Phosphorylates threonine in the C-terminal tail region of myosin II heavy chain. This phosphorylation is critical in regulating the assembly and disassembly of myosin II filament. Requires autophosphorylation for activity. | [[http://www.uniprot.org/uniprot/MHCKA_DICDI MHCKA_DICDI]] Phosphorylates threonine in the C-terminal tail region of myosin II heavy chain. This phosphorylation is critical in regulating the assembly and disassembly of myosin II filament. Requires autophosphorylation for activity. | ||
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== Publication Abstract from PubMed == | |||
The alpha-kinases are a widely expressed family of serine/threonine protein kinases that exhibit no sequence identity with conventional eukaryotic protein kinases. In this report we provide new information on the catalytic properties of the alpha-kinase domain of Dictyostelium myosin-II heavy chain kinase-A (termed A-CAT). Crystallization of A-CAT in the presence of MgATP yielded structures with AMP or adenosine in the catalytic cleft together with a phosphorylated Asp766 residue. The results show that the beta- and alpha-phosphoryl groups are transferred either directly or indirectly to the catalytically essential Asp766. Biochemical assays confirmed that A-CAT hydrolyzed ATP, ADP and AMP with kcat values of 1.9, 0.6 and 0.32 min-1, respectively, and showed that A-CAT can use ADP to phosphorylate peptides and proteins. Binding assays using fluorescent 2/3-O-(N-Methyl-anthraniloyl) analogs of ATP and ADP yielded Kd values for ATP, ADP, AMP and adenosine of 20, 60, 160 and 45 micromole, respectively. Site-directed mutagenesis showed that Glu713, Leu716 and Lys645, all of which interact with the adenine base, were critical for nucleotide binding. Mutation of the highly conserved Gln758, which chelates a nucleotide-associated Mg2+ ion, eliminated catalytic activity, whereas loss of the highly conserved Lys722 and Arg592 decreased kcat for kinase and ATPase activities by 3-6-fold. Mutation of Asp663 impaired kinase activity to a much greater extent than ATPase, indicating a specific role in peptide substrate binding, whereas mutation of Gln768 doubled ATPase activity, suggesting that it may act to exclude water from the active site. | |||
Characterization of the Catalytic and Nucleotide Binding Properties of the Alpha-kinase domain of Dictyostelium Myosin-II Heavy Chain Kinase A.,Yang Y, Ye Q, Jia Z, Cote GP J Biol Chem. 2015 Aug 10. pii: jbc.M115.672410. PMID:26260792<ref>PMID:26260792</ref> | |||
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | |||
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== References == | |||
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</StructureSection> | </StructureSection> | ||