Assembly properties of amino- and carboxyl-terminally truncated neurofilament NF-H proteins with NF-L and NF-M in the presence and absence of vimentin.
To understand the assembly characteristics of the high-molecular-weight neurofilament protein (NF-H), carboxyl- and amino-terminally deleted NF-H proteins were examined by transiently cotransfecting mutant NF-H constructs with the other neurofilament triplet proteins, low- and middle-molecular-weight neurofilament protein (NF-L and NF-M, respectively), in the presence or absence of cytoplasmic vimentin. The results confirm that NF-H can coassemble with vimentin and NF-L but not with NF-M into filamentous networks. Deletions from the amino-terminus show that the N-terminal head is necessary for the coassembly of NF-H with vimentin, NF-L, or NF-M/vimentin. However, headless NF-H or NF-H from which the head and a part of the rod is removed can still incorporate into an NF-L/vimentin network. Deletion of the carboxyl-terminal tail of NF-H shows that this region is not essential for coassembly with vimentin but is important for coassembly with NF-L into an extensive filamentous network. Carboxyl-terminal deletion into the alpha-helical rod results in a dominant-negative mutant, which disrupts all the intermediate filament networks. These results indicate that NF-L is the preferred partner of NF-H over vimentin and NF-M, the head region of NF-H is important for the formation of NF-L/NF-H filaments, and the tail region of NF-H is important to form an extensive network of NF-L/NF-H filaments.
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Department of Pathology, Columbia University College of Physicians and Surgeons, New York, New York, USA.
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D001483:Base Sequence; D017353:Gene Deletion; D006801:Humans; D007382:Intermediate Filaments / Q000502:physiology; D008969:Molecular Sequence Data; D009154:Mutation; D016900:Neurofilament Proteins / Q000235:genetics* / Q000502:physiology*; D014407:Tumor Cells, Cultured; D014746:Vimentin / Q000737:chemistry / Q000494:pharmacology*
D016900:Neurofilament Proteins; D014746:Vimentin; C044882:neurofilament protein L; C051774:neurofilament protein H; C061195:neurofilament protein M