Myelin proteolipid protein (PLP), but not DM-20, is an inositol hexakisphosphate-binding protein.
Myelin proteolipid protein (PLP) and its alternatively spliced isoform, DM-20, are the major integral membrane proteins of central nervous system myelin. It is known that PLP and DM-20 are delivered to myelin by a finely regulated vesicular transport system in oligodendrocytes. Evolutionarily, it is believed that ancestral DM-20 acquired a PLP-specific exon to create PLP, after which PLP/DM-20 became a major component of central nervous system myelin. We purified PLP as an inositol 1,3,4,5-tetrakisphosphate-binding protein after solubilization in a non-organic solvent. However, under the isotonic condition, PLP binds inositol hexakisphosphate (InsP6) significantly, not inositol 1,3,4,5-tetrakisphosphate. Most of the InsP6-binding proteins are involved in vesicular transport, suggesting the involvement of PLP in vesicular transport. We separated DM-20 from PLP by CM-52 chromatography and showed that DM-20 has no InsP6 binding activity. These findings indicate that the PLP-specific domain confers the InsP6 binding activity and this interaction may be important for directing PLP transport to central nervous system myelin.
Yamaguchi
Y
Y
Laboratory of Neural Information, National Institute for Physiological Sciences, Okazaki National Research Institutes, Okazaki, Aichi 444, Japan. ikenaka@nips.ac.jp
Ikenaka
K
K
Niinobe
M
M
Yamada
H
H
Mikoshiba
K
K
D000818:Animals; D001667:Binding, Competitive; D001692:Biological Transport; D002462:Cell Membrane / Q000378:metabolism; D002531:Cerebellum / Q000378:metabolism*; D002846:Chromatography, Affinity; D002848:Chromatography, DEAE-Cellulose; D007295:Inositol Phosphates / Q000378:metabolism / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D018991:Myelin Proteolipid Protein / Q000302:isolation & purification / Q000378:metabolism*; D009419:Nerve Tissue Proteins; D010833:Phytic Acid / Q000378:metabolism*; D013379:Substrate Specificity
D007295:Inositol Phosphates; D018991:Myelin Proteolipid Protein; D009419:Nerve Tissue Proteins; C047516:Plp1 protein, mouse; C081655:inositol-1,3,4,5-tetrakisphosphate; D010833:Phytic Acid