Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Ain't that a Sidekick in the head

Credit: Reprinted with permission from Elsevier Science

Neurons in the developing brain send out axons that must navigate a complex meshwork of cells to specific layers called laminae. Joshua Shanes and colleagues now show us how these axons reach their destination with precision. In the 6 September issue of Cell, they demonstrate that Sidekick-1 and -2, transmembrane proteins in the immunoglobulin superfamily, guide axon terminals to specific laminae. This confocal image shows concentrated expression of Sidekick-2 (green) near the synaptic cleft, sandwiched between presynaptic terminals (red) and the postsynaptic apparatus (blue) in the chicken retina. Expression of Sidekick-1 in presynaptic cells targets axons to laminae expressing Sidekick-1. A similar pattern occurs between Sidekick-2-expressing presynaptic cells and Sidekick-2 laminae. The authors went on to demonstrate that each Sidekick binds to its own kind in vitro, and that in the retina their expression patterns do not overlap. Ectopic expression of either protein in Sidekick-negative cells redirects axon terminals to laminae expressing the same Sidekick. The data indicate that expression of Sidekicks in pre- and postsynaptic neurons directs formation of the synapse.


Rights and permissions

Reprints and Permissions

About this article

Cite this article

Stebbins, M. Ain't that a Sidekick in the head. Nat Med 8, 1085 (2002).

Download citation

  • Issue Date:

  • DOI:


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing