title: Effect of phosphorylation on 68 KDa neurofilament subunit protein assembly by the cyclic AMP dependent protein kinase in vitro.
abstract: The effect of phosphorylation by cyclic AMP dependent protein kinase on the assembly of the core-forming 68 KDa neurofilament subunit protein (NF-L) was studied in vitro by fluorescence energy transfer and electron microscopy. Phosphorylation of unassembled NF-L in a low ionic strength buffer by cyclic AMP dependent protein kinase led to the incorporation of 1-2 phosphate groups/mole protein. Assembly of this phosphorylated NF-L was inhibited significantly; compared to non-phosphorylated NF-L, the critical concentration of phosphorylated NF-L was raised by greater than 30-fold. Assembled NF-L filaments could also be phosphorylated by cyclic AMP dependent protein kinase indicating that the sites were accessible. Phosphorylation of NF-L in the filamentous state induced their disassembly. The results suggest that phosphorylation by cyclic AMP dependent protein kinase is a possible means to modulate the assembly state of NF-L.
authors.affiliation: Department of Neuropsychiatry, Osaka University Medical School, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Nakamura
authors.forename: M
authors.initials: M
authors.lastname: Takeda
authors.forename: K J
authors.initials: KJ
authors.lastname: Angelides
authors.forename: T
authors.initials: T
authors.lastname: Tanaka
authors.forename: K
authors.initials: K
authors.lastname: Tada
authors.forename: T
authors.initials: T
authors.lastname: Nishimura
mesh_terms: D000818:Animals; D002417:Cattle; D007381:Intermediate Filament Proteins / Q000302:isolation & purification / Q000378:metabolism* / Q000648:ultrastructure; D007700:Kinetics; D046911:Macromolecular Substances; D008854:Microscopy, Electron; D016900:Neurofilament Proteins; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D013116:Spinal Cord / Q000378:metabolism
chemical_list: D007381:Intermediate Filament Proteins; D046911:Macromolecular Substances; D016900:Neurofilament Proteins; C044882:neurofilament protein L; D011494:Protein Kinases