Axonal neurofilaments are closely packed in mice lacking the phosphorylated NF-M tail (bottom).

Axons are fattened by an unexpected neurofilament (NF) subunit, according to Garcia et al. (page 1011) and Rao et al. (page 1021), who find that more phosphorylation sites are not necessarily better when it comes to driving axon expansion.

The radial growth-inducing subunit is one of three that make up NFs. The COOH-terminal tails of two of these subunits, NF-H and NF-M, extend perpendicular to the main NF axis and thus bridge NFs with adjacent NFs, actin filaments, or microtubules. These COOH-terminal tails are phosphorylated in response to myelination, which also initiates a tenfold expansion in volume that is critical for fast conduction of action potentials. As NF-H has 51 phosphorylation sites in its COOH- terminal tail, and NF-M has just 7, NF-H was assumed to be the...

The Rockefeller University Press
2003
The Rockefeller University Press
2003
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