CELLULAR AND MOLECULAR-BIOLOGY OF NEURONAL INTERMEDIATE FILAMENTS

This chapter describes the structural properties of neuronal intermediate filaments (IFs) and how these properties influence neuronal-IF assembly dynamics and axonal-transport kinetics. IF proteins, including the neuronal IFs, belong to a complex, multigene family, which has been divided into six types of genes. IF proteins typically contain a central, α-helical rod domain of approximately 310 amino acids, which is subdivided into three coils by short, non-α-helical linker domains of more variable length and sequence. The rod domain is highly conserved in primary and secondary structure among the IFs, particularly at the ends. This rod domain confers a fibrous character upon IF proteins, and by virtue of its hydrophobic heptad repeats yields a hydrophobic strip along one side of the helix to promote dimerization. The amino-terminal head domains of the neuronal IFs exhibit only limited sequence homologies, including an 11-amino acid-stretch highly conserved between rat α-internexin and NF-M. Rich in arginine, they are highly basic, and the prevalence of glycine, proline, and serine residues predicts a structure dominated by β-turns and β-sheets. © 1991, Elsevier Science & Technology. All rights reserved.