AIS neurofascin'd to matrix

Thoughts and movements depend on the axon initial segment (AIS), which instigates action potentials. On page 875, Hedstrom et al. show how a protein crucial for nerve development helps build the AIS by coating it with a layer of extracellular matrix.

The AIS passes on an action potential to the nodes of Ranvier, which relay it along the rest of the axon. Although the two kinds of structures harbor almost the same molecules, they form differently. In the peripheral nervous system, neighboring Schwann cells draw the axonal protein neurofascin-186 (NF-186) to an incipient node. In turn, NF-186 lures other components, such as the cytoskeleton protein ankyrin G and sodium channels. The AIS, by contrast, assembles from its own internal signals. Studies disagree about which molecule recruits the others.

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