What is the correct physical picture of reflectin protein self-assembly?

Squids and octopuses occupy every optical niche of the ocean, from mud flats to the midwater abyss. In every one of these optical scenarios, each species' highly sophisticated camouflage is driven by a layer of living cells in the skin containing ordered, sub-wavelength arrays of a high-refractive-index protein called reflectin. In some shallow contexts, this layer matches the albedo of a given species' background, while in open ocean contexts, bioluminescent light when scattered through this layer matches the radiance of the surrounding water. In all cases, these feats of photonic engineering are achieved via self-assembly of "reflectin" protein. Although almost two decades of research have elapsed since reflectins' discovery, we still do not have a clear enough physical picture of reflectin protein-protein interactions to know why some mixtures of these proteins make mirrors in vivo, while other mixtures of similar proteins make light guides. This talk explores and weighs the evidence for several novel hypotheses of reflectin assembly mechanisms, including the free energy of the proteins' association with lipid bilayers and the bilayers' corresponding physical phases; the evidence for true patchy-colloid physics in reflectins; the possibility of a surface-induced phase transition; and the possible role of flexible metal coordination. None of these possibilities are mutually exclusive. While we do not yet have a complete picture of this system, it is clear that squid are leveraging assembly constructs at the cutting edge of current physics knowledge that are worth serious consideration.