A protein complex that orients itself in the direction of a magnetic field and whose genes are present in many animal species is identified in a study published online this week in Nature Materials. The protein complex may underlie the ability of some animals to sense magnetic fields, and its properties could open up a broad range of applications where magnetic fields are used to modulate biological processes.

Animals of many species are able to sense the direction, intensity or inclination of the Earth’s magnetic field, and use this information as navigational cues. Although several biochemical models exist to explain such ability, much remains unknown about the underlying biological machinery that makes it possible.

By screening the genome of fruit flies on the basis of rational biological assumptions, Can Xie and colleagues identified a polymer-like protein (which they named MagR) that couples with units of a light-sensitive cryptochrome protein (Cry) and spontaneously aligns in the direction of external magnetic fields. They also show through biochemical and biophysical methods that the MagR/Cry complex is stable in the retina of pigeons and can also form in butterfly, rat, whale and human cells.

The authors note that the mechanism by which the MagR/Cry complex is able to sense magnetic fields and whether MagR/Cry is involved in animal magnetosensing remain unknown. Yet the discovery of such a compass-like protein complex could give rise to a broad range of new approaches for the magnetic-field-induced manipulation of macromolecules and even cell behaviour.