Disease relevance of NF-M

• Escherichia coli alkaline and wheat germ acid phosphatases increased the electrophoretic mobility of NF-H and NF-M by dephosphorylation, and induced the binding of NF-H to MTs [1].

High impact information on NF-M

• To establish whether Lys-Ser-Pro-Val(Ala) is the major site for in vivo NF phosphorylation, peptides based on the human NF-M repeat were synthesized and chemically phosphorylated [2].
• Phosphorylation of native and reassembled neurofilaments composed of NF-L, NF-M, and NF-H by the catalytic subunit of cAMP-dependent protein kinase [3].
• For NF-M, one major site (Thr48) lies within the NH2-terminal head domain, whereas the other (Thr431) is located at the tail domain [4].
• A novel proline-directed protein kinase previously identified and purified from bovine brain has been found in this study to phosphorylate NF-H and NF-M at sites identical to those phosphorylated by HeLa cell p34cdc2 kinase [5].
• Dephosphorylated NF-M was phosphorylated only half as much as native NF-M; this is consistent with the known substrate specificity of the kinase [6].

Biological context of NF-M

• When mapping with the amino acid sequence of neurofilament, we finally demonstrate Ser603-Pro, one of the in vivo sites in NF-M, as the major site phosphorylated by kinase FA/GSK-3 alpha [7].
• Brains of human and some animals could be discriminated by detecting NF-L or NF-M, although the species specificity of NF-H was not good [8].

Anatomical context of NF-M

• Reconstitution of short intermediate filaments was observed upon dialysis of denatured NF-M versus a reconstitution buffer [9].
• The radioiodinated neurofilament proteins (untreated and dephosphorylated) were incubated in the presence and absence of calpain from rabbit skeletal muscle, and the degradation rates of large (NF-H), mid-sized (NF-M) and small (NF-L) neurofilament polypeptides were analysed by SDS/polyacrylamide-gel electrophoresis and autoradiography [10].
• We carried out immunolabeling studies of purified bovine spinal cord neurofilaments (NFs) and filaments reconstituted from several combinations of the NF triplet polypeptides, NF-H, NF-M, and NF-L [11].
• CKI from rabbit reticulocytes phosphorylated all three NF subunits (NF-H, NF-M and NF-L) [12].

Associations of NF-M with chemical compounds

• Kinase FA/GSK-3 alpha phosphorylates NF-M predominantly on serine residue [7].
• By contrast, intact, dephosphorylated NF-H subunits were unable to prevent AlCl3-induced alteration of native NF-M electrophoretic migration [13].

Analytical, diagnostic and therapeutic context of NF-M

• A circular dichroism spectrum of NF-M in 10 mM Tris was typical of alpha + beta proteins [9].
• Polyacrylamide gel electrophoresis (PAGE) and immunoblot analyses revealed the fragmentation of oxidized NF proteins, predominantly NF-H and NF-M [14].
• Individual components of the NF triplet, i.e. NF-L, NF-M and NF-H, were purified by DE-52 and Mono-Q anion exchange chromatographies in the presence of 6 M-urea and were assembled in various combinations into filaments [15].
• In this report, the phosphorylation sites of neurofilament protein of medium molecular mass (NF-M) by protein kinase FA/glycogen synthase kinase 3 alpha (kinase FA/GSK-3 alpha) were determined by two-dimensional electrophoresis/TLC, phosphoamino acid analysis, HPLC, Edman degradation, and peptide sequencing [7].
• Titration of NF-L with NF-M indicated that complex formation was complete at an approximately equimolar ratio of the two proteins [16].

References