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Tyrosine Phosphorylation of PNS Myelin P 0 Occurs in the Cytoplasmic Domain and Is Maximal During Early Development
Author(s) -
Iyer Srinivas,
Bianchi Roberto,
Eichberg Joseph
Publication year - 2000
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 - 10.1046/j.1471-4159.2000.0750347.x
Subject(s) - phosphorylation , myelin , tyrosine , tyrosine phosphorylation , cytoplasm , chemistry , microbiology and biotechnology , myelin sheath , neuroscience , protein tyrosine phosphatase , domain (mathematical analysis) , biology , biochemistry , central nervous system , mathematical analysis , mathematics
Abstract P 0 , the major protein of PNS myelin, is considered to play a critical role in the compaction and stabilization of myelin lamellae. The protein undergoes extensive posttranslational modifications, including phosphorylation at multiple serine moieties in the cytoplasmic region. Recently, we demonstrated that P 0 is phosphorylated on one or more tyrosine residues in rat nerve homogenates after incubation. In this study, we show that P 0 phosphorylated on tyrosine is also present in the intact animal. The proportion of P 0 molecules phosphorylated on tyrosine is highest during the first postnatal week, a period that coincides with the most rapid period of myelin deposition in the PNS. A peptide that constitutes the cytoplasmic domain was isolated from purified P 0 and shown by immunochemical and chemical means to be phosphorylated on the tyrosine corresponding to Y 191 in the intact protein. No evidence was obtained supporting the possibility that P 0 is phosphorylated on other tyrosine residues. The sequence of amino acids surrounding Y 191 resemble known substrate phosphorylation sites for some nonreceptor cytoplasmic tyrosine kinases, as well as tyrosine‐based recognition signals associated with clathrin vesicle‐mediated cndocytosis.