ADP-ribosylation of human myelin basic protein.
When isolated myelin membranes were ADP-ribosylated by [32P]NAD+ either in the absence of toxin (by the membrane ADP-ribosyltransferase) or in the presence of cholera toxin, the same proteins were ADP-ribosylated in both cases and myelin basic protein (MBP) was the major radioactive product. Therefore, cholera toxin was considered a good model for ADP-ribosylation of myelin proteins. Although purified human MBP migrates as a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis with a molecular mass of 20 kDa, the microheterogeneity that is masked under these conditions can be clearly demonstrated on alkaline-urea gels at pH 10.6. At this pH, MBP is resolved into several components that differ one from the other by a single charge (charge isomers). These charge isomers can be resolved on CM52 columns at pH 10.6, and several can be ADP-ribosylated. Component 1 (C-1), the most cationic charge isomer, incorporated 1.79 mol of ADP-ribose/mol of protein. C-2 and C-3 (which differ from C-1 by the loss of one and two positive charges, respectively) incorporated slightly less at 1.67 and 1.63 mol of ADP-ribose/mol of protein, respectively, whereas C-8, the least cationic, incorporated less than 0.11 mol/mol of protein. In the presence of neutral hydroxylamine, the ADP-ribosyl bond was shown to have a half-life of about 80 min, suggesting an N-glycosidic linkage between ADP-ribose and an arginyl residue of the protein.(ABSTRACT TRUNCATED AT 250 WORDS)
Boulias
C
C
Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada.
Moscarello
M A
MA
D000246:Adenosine Diphosphate Ribose / Q000378:metabolism*; D000595:Amino Acid Sequence; D002772:Cholera Toxin / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D003172:Complement C1 / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D019811:Hydroxylamine; D006898:Hydroxylamines / Q000494:pharmacology; D008969:Molecular Sequence Data; D004676:Myelin Basic Protein / Q000032:analysis / Q000378:metabolism*; D009243:NAD / Q000494:pharmacology; D015398:Signal Transduction / Q000502:physiology
D003172:Complement C1; D006898:Hydroxylamines; D004676:Myelin Basic Protein; D009243:NAD; D000246:Adenosine Diphosphate Ribose; D019811:Hydroxylamine; D002772:Cholera Toxin