Palmitoylation is a sorting determinant for transport to the myelin membrane.
Myelin is a specialized membrane enriched in glycosphingolipids and cholesterol that contains a restricted set of proteins. The mechanisms by which oligodendrocytes target myelin components to myelin are not known. To identify the sorting determinants for protein transport to myelin, we used a primary oligodendrocyte culture system in which terminal differentiation is synchronized and there is excessive deposition of myelin-like membranes (MLMs). Because several myelin proteins are palmitoylated, we explored the role of acylation in protein transport to MLMs. We found that palmitoylation-deficient mutants of a major myelin protein, proteolipid protein (PLP/DM20), were less efficiently targeted to MLMs. The N-terminal 13 amino acids of PLP/DM20, which are palmitoylated at three sites, were sufficient to direct a fluorescent fusion protein to MLMs. Mutagenesis of the N-terminal palmitoylation motif abolished the transport of the fusion protein to MLMs, indicating that palmitoylation is required for sorting to myelin. Similar results were obtained in myelinating co-cultures of oligodendrocytes and neurons. Furthermore, the combined farnesylation/palmitoylation signals from c-Ha-Ras and the N-terminal consensus sequence for dual palmitoylation from neuromodulin were sufficient for the transport of fluorescent fusion proteins to MLMs. Thus, we conclude that palmitoylation is a sorting determinant for transport to the myelin membrane.
Schneider
Anja
A
Department of Neurology, Hertie Institute for Clinical Brain Research, University of Tübingen, Hoppe-Seyler-Strausse 3, 72076 Tübingen, Germany.
Länder
Hanna
H
Schulz
Giselheid
G
Wolburg
Hartwig
H
Nave
Klaus-Armin
KA
Schulz
Jörg B
JB
Simons
Mikael
M
D000818:Animals; D002478:Cells, Cultured; D005229:Fatty Acids, Monounsaturated / Q000378:metabolism; D051379:Mice; D018991:Myelin Proteolipid Protein / Q000378:metabolism*; D009186:Myelin Sheath / Q000378:metabolism* / Q000648:ultrastructure; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009836:Oligodendroglia / Q000378:metabolism* / Q000648:ultrastructure; D011499:Protein Processing, Post-Translational / Q000502:physiology*; D021381:Protein Transport / Q000502:physiology
D005229:Fatty Acids, Monounsaturated; D018991:Myelin Proteolipid Protein; D009419:Nerve Tissue Proteins; C047516:Plp1 protein, mouse; C008757:palmitoleic acid