The human eye lens consists of a highly concentrated mix of several proteins. Protective proteins keep them from aggregating and clumping. If this protection fails, the lens blurs and the patient develops cataracts. Two research groups at the Department of Chemistry of the Technische Universitaet Muenchen (TUM) have succeeded in explaining the molecular architecture of this kind of protective protein. Their findings, which are published in PNAS (Proceedings of the National Academy of Sciences).
Cells have a variety of protein complexes that manage vital tasks. The functions of these "molecular machines" depend largely on their three-dimensional structure. In the first instance, proteins are long chains of amino acids, like a long piece of woolen thread. So-called chaperones help them to fold in the desired three-dimensional form after their production. If this folding process fails, the protein thread becomes a useless tangle.
Small heat shock proteins (sHsps) are a particularly important group of chaperones. They prevent the clumping of proteins under stress conditions. αB-crystallin and αA-crystallin are the
main representatives of the sHsps found in humans. Whereas αA-crystallin mainly occurs in the eye lens, αB-crystallin is also very common in the brain and in the heart and muscle tissue. In the eye lens, they counteract diseases like cataracts. Malfunctions of the αB-crystallin in tissue cells can give rise to cancer and neurological defects, including Alzheimer's disease.