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 |
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Authors: | Dongming Sun Pompeo Macioce Steven S. M. Chin Ronald K. H. Liem |
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Affiliation: | Departments of Pathology, and Anatomy and Cell Biology, Columbia University College of Physicians and Surgeons, New York, New York, U.S.A.;and; Laboratorio di Biologia Cellulare, Istituto Superiore di Sanità, Rome, Italy |
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Abstract: | Abstract: 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 α-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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Keywords: | Neurofilament protein Vimentin Intermediate filament Filament network formation |
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