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.

The self-organizing properties of squid reflectin protein


Reflectins, a recently identified protein family that is enriched in aromatic and sulphur-containing amino acids, are used by certain cephalopods to manage and manipulate incident light in their environment. These proteins are the predominant constituent of nanoscaled photonic structures that function in static and adaptive colouration, extending visual performance and intra-species communication. Our investigation into recombinantly expressed reflectin has revealed unanticipated self-assembling and behavioural properties, and we demonstrate that reflectin can be easily processed into thin films, photonic grating structures and fibres. Our findings represent a key step in our understanding of the property–function relationships of this unique family of reflective proteins.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Light-organ platelets and native self-assembly of reflectin 1a protein from an insoluble precursor.
Figure 2: Solution casting of recombinant reflectin thin films.
Figure 3: Reflectin films exhibit shifts in the spectral interference peaks due to film swelling.
Figure 4: Surface diffraction gratings produced from reflectin/ionic liquid thin films.
Figure 5: Reflectin 1a fibres pulled from bulk precipitated protein.


  1. Vukusic, P. & Sambles, J. R. Photonic structures in biology. Nature 424, 852–855 (2003).

    Article  CAS  Google Scholar 

  2. Onslow, H. On a periodic structure in many insect scales and the cause of their iridescent colours. Phil. Trans. R. Soc. Lond. B 211, 1–74 (1921).

    Article  Google Scholar 

  3. Berthier, S. Iridescences: The Physical Colours of Insects (Springer, Berlin, 2006).

    Google Scholar 

  4. Johnsen, S. Cryptic and conspicuous colouration in the pelagic environment. Proc. R. Soc. Lond. B 269, 243–256 (2002).

    Article  Google Scholar 

  5. Johnsen, S. & Sosik, H. M. Cryptic colouration and mirror sides as camouflage strategies in near-surface pelagic habitats: Implications for foraging and predator avoidance. Limnol. Oceanogr. 48, 1277–1288 (2003).

    Article  Google Scholar 

  6. Griffiths, D. J., Winsor, H. & Luong-Van, T. Iridophores in the mantle of giant clams. Aust. Zool. 40, 319–326 (1992).

    Article  Google Scholar 

  7. Crookes, W. J. et al. Reflectins: The unusual proteins of squid reflective tissues. Science 303, 235–238 (2004).

    Article  CAS  Google Scholar 

  8. Land, M. F. The physics and biology of animal reflectors. Prog. Biophys. Mol. Biol. 24, 75–106 (1972).

    Article  CAS  Google Scholar 

  9. Denton, E. J., Land, F. R. S. & Land, M. F. Mechanisms of reflexion in silvery layers of fish and cephalopods. Proc. R. Soc. Lond. A 178, 43–61 (1971).

    Article  CAS  Google Scholar 

  10. Denton, E. J. On the organization of reflecting surfaces in some marine animals. Phil. Trans. R. Soc. B 258, 285–313 (1970).

    Article  CAS  Google Scholar 

  11. McFall-Ngai, M. J. & Montgomery, M. K. The anatomy and morphology of the adult bacterial light organ of Euprymna scolopes Berry (Cephalopoda: Sepiolidae). Biol. Bull. 147, 332–339 (1990).

    Article  Google Scholar 

  12. Montgomery, M. K. & McFall-Ngai, M. J. The muscle-derived lens of a squid bioluminescent organ is biochemically convergent with the ocular lens. Evidence for recruitment of aldehyde dehydrogenase as a predominant structural protein. J. Biol. Chem. 267, 20999–21003 (1992).

    CAS  Google Scholar 

  13. Weiss, J. L. et al. Methionine-rich repeat proteins: A family of membrane-associated proteins which contain unusual repeat regions. Biochim. Biophys. Acta 1668, 164–174 (2005).

    Article  CAS  Google Scholar 

  14. Cooper, K. M. & Hanlon, R. T. Correlation of iridescence with changes in iridophore platelet ultrastructure in the squid Lolliguncula brevis. J. Exp. Biol. 121, 451–455 (1986).

    CAS  Google Scholar 

  15. Cooper, K. M., Hanlon, R. T. & Budelmann, B. U. Physiological colour change in squid iridophores II. Ultrastructural mechanisms in Lolliguncula brevis. Cell Tissue Res. 259, 15–24 (1990).

    Article  CAS  Google Scholar 

  16. Mäthger, L. M., Collins, T. F. T. & Lima, P. A. The role of muscarinic receptors and intracellular Ca2+ in the spectral reflectivity changes of squid iridophores. J. Exp. Biol. 207, 1759–1769 (2004).

    Article  Google Scholar 

  17. Fincham, A. G., Moradian-Oldak, J. & Simmer, J. P. The structural biology of developing dental enamel. J. Struct. Biol. 126, 270–299 (1999).

    Article  CAS  Google Scholar 

  18. Eastoe, J. E. Organic matrix of tooth enamel. Nature 187, 411–412 (1960).

    Article  CAS  Google Scholar 

  19. Du, C., Falini, G., Fermani, S., Abbot, C. & Moradian-Oldak, J. Supramolecular assembly of amelogenin nanospheres into birefringent microribbons. Science 307, 1450–1454 (2005).

    Article  CAS  Google Scholar 

  20. Makin, O. S. & Serpell, L. C. Structures for amyloid fibrils. Fed. Eur. Bioch. Soc. J. 272, 5950–5961 (2005).

    CAS  Google Scholar 

  21. Swatloski, R. P., Spear, R. K., Holbrey, J. D. & Rogers, R. D. Dissolution of cellulose with ionic liquids. J. Am. Chem. Soc. 124, 4974–4975 (2002).

    Article  CAS  Google Scholar 

  22. Phillips, D. M. et al. Dissolution and regeneration of Bombyx mori silk fibroin using ionic liquids. J. Am. Chem. Soc. 126, 14350–14351 (2004).

    Article  CAS  Google Scholar 

  23. Sundd, M., Kundu, S. & Jagannadham, M. V. Alcohol-induced conformational transitions in ervatamin C. An alpha-helix to beta-sheet switchover. J. Protein Chem. 19, 169–176 (2000).

    Article  CAS  Google Scholar 

  24. Kumaran, S. & Roy, R. P. Helix-enhancing propersity of fluoro and alkyl alcohols: Influence of pH, temperature and cosolvent concentration on the helical conformation of peptides. J. Pep. Res. 53, 284–293 (1999).

    Article  CAS  Google Scholar 

  25. Ober, C. Persistence pays off. Science 296, 859–861 (2002).

    Article  CAS  Google Scholar 

  26. Qi, M. et al. A three-dimensional optic photonic crystal with designed point defects. Nature 429, 538–542 (2004).

    Article  CAS  Google Scholar 

Download references


This work has been financially supported by DARPA (DSO) and AFOSR. We acknowledge M. McFall-Ngai (NIH AI50611) and E.G. Ruby (NIH RR 12294) for providing us with squid tissue. We thank M. Gupta for assistance with white-light interferometry imaging and D. Morse, R. Hanlon and M. Yustak for helpful discussions.

Author information

Authors and Affiliations


Corresponding author

Correspondence to Rajesh R. Naik.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

Supplementary figures S1-S6 (PDF 894 kb)

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Kramer, R., Crookes-Goodson, W. & Naik, R. The self-organizing properties of squid reflectin protein. Nature Mater 6, 533–538 (2007).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


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