Alpha-kinase domain of Dictyostelium discoideum VwkA and similar domains
Dictyostelium discoideum alpha-protein kinase VwkA is also called von Willebrand factor A alpha-kinase or vWF kinase. It influences myosin II abundance and assembly behavior as vWKA gene disruption leads to significant myosin II overassembly. VwkA also serves a critical conserved role in the periodic contractions of the contractile vacuole through its regulation of the myosin II cortical cytoskeleton. It contains a vWFa domain (named after its homology to von Willebrand factor A, a plasma glycoprotein essential for proper blood clotting) and a C-terminal alpha-kinase domain. Alpha-kinase is an atypical protein kinase catalytic domain with no detectable similarity to conventional protein serine/threonine kinases. The alpha-kinase family was named after the unique mode of substrate recognition by its initial members, the Dictyostelium heavy chain kinases, which targeted protein sequences that adopt an alpha-helical conformation. More recently, alpha-kinases were found to also target residues in non-helical regions.
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