title: Reversible self-phosphorylation of asparaginase complex in Leptosphaeria michotii: characterization of associated protein kinase and protein phosphatase activities.
abstract: Regulation of the asparaginase activity rhythm in L. michotii has previously been shown to be dependent on a reversible phosphorylation process. Asparaginase was isolated as a purified protein complex having self-phosphorylating capacities, which were analyzed. In vivo phosphorylation of asparaginase complex was performed synchronously with the rhythm of asparaginase activity. In vitro self-phosphorylation of asparaginase complex resulted from the activity of an ATP-Mg2+-dependent protein kinase, which phosphorylated protein at threonine residues and was not dependent on cyclic AMP, Ca2+ or calmodulin. Dephosphorylation of this complex was due to a Mg2+-Zn2+-dependent protein phosphatase, molybdate inhibited, the specificity of which, for low-molecular-weight nonprotein phosphoesters, was broad.
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D001203:Ascomycota / Q000201:enzymology*; D001215:Asparaginase / Q000378:metabolism*; D009097:Multienzyme Complexes / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D013997:Time Factors; D013098:Xylariales / Q000201:enzymology*
chemical_list: D009097:Multienzyme Complexes; D011494:Protein Kinases; D000469:Alkaline Phosphatase; D010749:Phosphoprotein Phosphatases; D001215:Asparaginase