What prevents the movement of membrane molecules between axonal and somatodendritic domains is unclear. In this issue, Albrecht et. al. (2016. J. Cell Biol. http://dx.doi.org/10.1083/jcb.201603108) demonstrate via high-speed single-particle tracking and superresolution microscopy that lipid-anchored molecules in the axon initial segment are confined to membrane domains separated by periodically spaced actin rings.
© 2016 Huang and Rasband.