In Vitro and in Vivo Phosphorylation of Myelin Basic Protein by Exogenous and Endogenous Adenosine 3′ : 5′-Monophosphate-dependent Protein Kinases in Brain

摘要: Abstract Myelin basic protein, an encephalitogenic was phosphorylated by adenosine 3' : 5'-monophosphate (cyclic AMP)-dependent protein kinase from bovine brain, and its phosphorylation stimulated cyclic AMP. The ability of the to serve as substrate for comparable that histone fractions better than casein, protamine, or phosvitin. apparent Km enzyme 2 x 10-5 m. showed a different migration on disc gel electrophoresis native suggesting modification molecule resulted in alteration physicochemical properties protein. caused activation kinase, preincubation with substantial increase AMP-independent activity. Protein modulator inhibited activity presence absence AMP when myelin used substrate. Amino acid residues which were brain seryl threonyl. maximum amount phosphate incorporated into 3.80 moles per mole 3.6 times higher basis weight. Native contained 0.20 phosphorus 0.07 0.09 associated phosphoserine phosphothreonine, respectively. An extensively washed fraction endogenous catalyzed ATP Mg2+. In vivo observed injection [32P]orthophosphate ventricle rat brain. highest specific radioactivity amount, compared crude homogenate fraction. Incorporated released course time. results indicate dephosphorylation may be dynamic state turnover rate relatively rapid.