Neurofilament

Neurofilaments are the type IV family of intermediate filaments that is found in high concentrations along the axons of vertebrate neurons.

The three types of neurofilament proteins coassemble in vivo, forming a heteropolymer that contain NF-L plus one of the others. The NF-H and NF-M proteins have lengthy C-terminal tail domains that bind to neighboring filaments, generating aligned arrays with a uniform interfilament spacing.

During axonal growth, new neurofilament subunits are incorporated all along the axon in a dynamic process that involves the addition of subunits along the filament length, as well as the addition of subunits at the filament ends.

After an axon has grown and connected with its target cell, the diameter of the axon may increase as much as fivefold.

The level of neurofilament gene expression seems to directly control axonal diameter, which in turn controls how fast electrical signals travel down the axon.