Selective activation of the two catalytic sites in the ATP.Mg-dependent phosphoprotein phosphatase by kinase Fa and Mn2+ ion.
1. Although Mn2+ could mimic kinase FA/ATP.Mg to activate ATP.Mg-dependent protein phosphatase, strong indications have been obtained that the Mn2(+)-activated and FA/ATP.Mg-activated phosphatase forms are not identical in terms of their substrate specificities and catalytic properties. 2. Both Mn2(+)-activated and FA/ATP.Mg-activated phosphatase forms readily dephosphorylate 32P-labeled phosphorylase a and myelin basic protein (MBP), however the Mn2(+)-activated phosphatase displays activity preferentially against [32P]MBP and FA/ATP.Mg-activated phosphatase preferentially dephosphorylates [32P]phosphorylase a, representing a unique control mechanism to regulate the substrate specificity of multisubstrate protein phosphatase in mammalian tissues.
Yang
S D
SD
Institute of Molecular Cell Biology, Chang Gung Medical College, Tao-Yuan, Taiwan, R.O.C.
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D004789:Enzyme Activation; D008345:Manganese / Q000494:pharmacology*; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D011494:Protein Kinases / Q000494:pharmacology*; D051381:Rats; D013379:Substrate Specificity
D008345:Manganese; D000255:Adenosine Triphosphate; D011494:Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D010749:Phosphoprotein Phosphatases