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Phosphorylation of Myelin‐Associated Glycoprotein In Vivo and In Vitro Occurs Only in the Cytoplasmic Domain of the Large Isoform
Author(s) -
Edwards Aled M.,
Braun Peter E.,
Bell John C.
Publication year - 1989
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1989.tb10934.x
Subject(s) - phosphorylation , dephosphorylation , in vivo , myelin , gene isoform , in vitro , biochemistry , cytoplasm , myelin associated glycoprotein , biology , glycoprotein , microbiology and biotechnology , chemistry , phosphatase , central nervous system , gene , endocrinology
Myelin‐associated glycoprotein (MAG) was radioactively labelled with 32 P both in intact brain and in myelin membrane preparations. Chemical deglycosylation of the phosphorylated products revealed that only one of the MAG isoforms (L‐MAG) is labelled in vitro. Furthermore, the phosphorylation events in vivo and in vitro are confined to the cytoplasmic portion of the L‐MAG isoform. Tryptic mapping of L‐MAG labelled both in vivo and in vitro revealed that the majority of the sites phosphorylated in intact brain are also phosphorylated in myelin membrane preparations; however, the extent of phosphorylation at individual sites is variable. The results demonstrate that partially purified myelin membrane preparations can be used to study the enzymes responsible for MAG phosphorylation and dephosphorylation events in vivo.