Published online May 14, 2007
doi:10.1083/jcb.200608060
The Journal of Cell Biology, Vol. 177, No. 4, 707-716
The Rockefeller University Press, 0021-9525 $30.00
© 2007 Gaboreanu et al.
Myelin protein zero/P0 phosphorylation and function require an adaptor protein linking it to RACK1 and PKC
Ana-Maria Gaboreanu1,
Ronald Hrstka1,
Wenbo Xu2,3,
Michael Shy2,3,
John Kamholz2,3,
Jack Lilien1, and
Janne Balsamo1
1 Department of Biological Sciences, The University of Iowa, Iowa City, IA 52242
2 Department of Neurology and 3 Center for Molecular Medicine and Genetics, Wayne State University, Detroit, MI 48202
Correspondence to Jack Lilien: jack-lilien{at}uiowa.edu
Point mutations in the cytoplasmic domain of myelin protein zero (P0; the major myelin protein in the peripheral nervous system) that alter a protein kinase C
(PKC
) substrate motif (198HRSTK201) or alter serines 199 and/or 204 eliminate P0-mediated adhesion. Mutation in the PKC
substrate motif (R198S) also causes a form of inherited peripheral neuropathy (Charcot Marie Tooth disease [CMT] 1B), indicating that PKC
-mediated phosphorylation of P0 is important for myelination. We have now identified a 65-kD adaptor protein that links P0 with the receptor for activated C kinase 1 (RACK1). The interaction of p65 with P0 maps to residues 179197 within the cytoplasmic tail of P0. Mutations or deletions that abolish p65 binding reduce P0 phosphorylation and adhesion, which can be rescued by the substitution of serines 199 and 204 with glutamic acid. A mutation in the p65-binding sequence G184R occurs in two families with CMT, and mutation of this residue results in the loss of both p65 binding and adhesion function.
Abbreviations used in this paper: CBP, CaM-binding peptide; CMT, Charcot Marie Tooth disease; MBP, maltose-binding protein; PNS, peripheral nervous system; RACK1, receptor for activated C kinase 1.

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