title: Acuity of a cryptochrome and vision-based magnetoreception system in birds.
abstract: The magnetic compass of birds is embedded in the visual system and it has been hypothesized that the primary sensory mechanism is based on a radical pair reaction. Previous models of magnetoreception have assumed that the radical pair-forming molecules are rigidly fixed in space, and this assumption has been a major objection to the suggested hypothesis. In this article, we investigate theoretically how much disorder is permitted for the radical pair-forming, protein-based magnetic compass in the eye to remain functional. Our study shows that only one rotational degree of freedom of the radical pair-forming protein needs to be partially constrained, while the other two rotational degrees of freedom do not impact the magnetoreceptive properties of the protein. The result implies that any membrane-associated protein is sufficiently restricted in its motion to function as a radical pair-based magnetoreceptor. We relate our theoretical findings to the cryptochromes, currently considered the likeliest candidate to furnish radical pair-based magnetoreception.
authors.affiliation: Frankfurt Institute for Advanced Studies, Goethe University, Frankfurt am Main, Germany.
authors.forename: Ilia A
authors.initials: IA
authors.lastname: Solov'yov
authors.forename: Henrik
authors.initials: H
authors.lastname: Mouritsen
authors.forename: Klaus
authors.initials: K
authors.lastname: Schulten
mesh_terms: D000818:Animals; D001717:Birds / Q000378:metabolism* / Q000502:physiology; D002940:Circadian Rhythm; D056931:Cryptochromes / Q000737:chemistry / Q000378:metabolism*; D008280:Magnetics; D008954:Models, Biological; D008958:Models, Molecular; D055254:Night Vision / Q000502:physiology; D009949:Orientation / Q000502:physiology; D011487:Protein Conformation; D012160:Retina / Q000378:metabolism; D014785:Vision, Ocular
chemical_list: D056931:Cryptochromes