The axon is a specialized projection that emerges from the soma (cell body) of a neuron. Axons propagate action potentials down their length, ultimately leading to neurotransmitter release at the axon terminals.
The proximal portion of an axon is represented by the AIS (Axon Initial Segment), which separates the somatodendritic compartment of a neuron from the axon, and is also the site of axon potential initiation by virtue of the high density of voltage-gated ion channels found there.
Ankyrin-G is a multidomain protein that localizes specifically to the AIS where it serves as a scaffolding protein and master organizer of the axon initial segment. In this role Ankyrin-G (Ank3) anchors voltage-gated sodium channels (Nav channels), structural proteins (Beta-IV-Spectrin), and cell adhesion proteins (Neurofascin) into a discrete domain at the proximal end of the developing axon to form the axon initial segment (AIS).
The high density of each of these different proteins (Ankyrin-G, Nav channels, Beta-IV-Spectrin, and Neurofascin) at the axon initial segment makes each of these proteins highly-specific axon markers. The more distal region of the mature axon can also be identified by expression of the microtubule-associated protein tau (which serves as an excellent marker of the distal axon).
Examples of some of our highly specific axonal markers are shown below:
Anti-Pan-Nav1 antibody: Neuromab 75-405 (pictured above with anti-Pan Nav1 staining in red, marking the axon initial segments)
Anti-Beta IV Spectrin antibody: Neuromab 75-377 pictured above and showing axon initial segment staining of cortical neurons.