Localization of peptidylarginine deiminase type II in a stage-specific immature oligodendrocyte from rat cerebral hemisphere

Myelin basic protein (MBP) is composed of multiple charged isomers as the p roducts of various posttranslational modifications, The least cationic comp onent contains six citrulline residues converted from arginine residues by peptidylarginine deiminase (PAD). The modified MBP differs markedly from un modified MBP in the ability to aggregate acidic lipid vesicles, However, th e localization of PAD in brain has remained rather elusive. We performed We stern blotting and immunocytochemical analyses of PAD type II and found tha t it was present in stage-specific immature oligodendrocytes but not in eit her type-1 astrocytes or neu ro ns, We also confirmed that only the oligode ndrocyte homogenate contained the PAD activity utilizing a sensitive method to detect citrulline-containing proteins. These data suggest that PAD type II localized in oligodendrocytes is responsible for deiminating MBP. (C) 1 999 Elsevier Science Ireland Ltd. All rights reserved.