Cytoplasmic O-GlcNAc Modification of the Head Domain and the KSP Repeat Motif of the Neurofilament Protein Neurofilament-H

• Published in: The Journal of biological chemistry Vol. 271; no. 34; pp. 20845 - 20852
• Main Authors: Dong, Dennis L.-Y., Xu, Zuo-Shang, Hart, Gerald W., Cleveland, Don W.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 23.08.1996; American Society for Biochemistry and Molecular Biology
• Subjects: Acetylglucosamine - metabolism; Amino Acid Sequence; Animals; Glycopeptides - chemistry; Glycosylation; Male; Molecular Sequence Data; Nerve Tissue Proteins - chemistry; Neurofilament Proteins - chemistry; Neurofilament Proteins - metabolism; Peptide Mapping; Protein Processing, Post-Translational; Rats; Repetitive Sequences, Nucleic Acid; Serine - chemistry; Spinal Cord - chemistry
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.271.34.20845

Neurofilaments, the major intermediate filaments in large myelinated neurons, are essential for specifying proper axonal caliber. Mammalian neurofilaments are obligate heteropolymers assembled from three polypeptides, neurofilament (NF)-H, NF-M, and NF-L, each of which undergoes phosphorylation at multiple sites. NF-M and NF-L are known to be modified by O-linked N-acetylglucosamine (O-GlcNAc) (Dong, D. L.-Y., Xu, Z.-S., Chevrier, M. R., Cotter, R. J., Cleveland, D. W., and Hart, G. W. (1993) J. Biol. Chem. 268, 16679-16687). Here we further report that NF-H is extensively modified by O-GlcNAc at Thr53, Ser54, and Ser56 in the head domain and, somewhat surprisingly, at multiple sites within the Lys-Ser-Pro repeat motif in the tail domain, a region in assembled neurofilaments known to be nearly stoichiometrically phosphorylated on each of the ∼50 KSP repeats. Beyond the earlier identified sites on NF-M and NF-L, O-GlcNAc sites on Thr19 and Ser34 of NF-M and Ser34 and Ser48 of NF-L are also determined here, all of which are localized in head domain sequences critical for filament assembly. The proximity of O-GlcNAc and phosphorylation sites in both head and tail domains of each subunit indicates that these modifications may influence one another and play a role in filament assembly and network formation.