Proteins Gallery

DNA nucleosome, molecular model

DNA nucleosome. Molecular model of a nucleosome, the fundamental repeating unit used to package DNA (deoxyribonucleic acid) inside cell nuclei. DNA is the molecule that carries the genetic code that forms the basis of all life on Earth. It is a long molecule and has to be tightly coiled to fit inside the nucleus. DNA's double helix structure is shown here as a coiled orange spiral. The DNA is coiled round a core of histone proteins (multicoloured ribbons). The ribbons represent the molecular structure of the histone proteins. Each set of two DNA loops around a histone core is known as a nucleosome. Further compacting and packaging (not seen here) form the denser forms of chromatin, and eventually the cell's chromosomes

© LAGUNA DESIGN/SCIENCE PHOTO LIBRARY

Prion disease treatment, artwork C018/1838

Prion disease treatment. Artwork of three pyramidal neurons (nerve cells). The cell at left is healthy. The cell at back has died because of a prion (pink) infection. The cell at right is infected with prions and has been treated with a PERK inhibitor drug (yellow). Prions are abnormal proteins that cause a group of fatal neurodegenerative diseases including BSE in cows and CJD in humans. Abnormal infectious prions directly change normal prions found in the brain to the abnormal form and prevent the synthesis of essential proteins. This leads to neuronal death. PERK inhibitors allow normal protein synthesis to continue, preventing neurodegeneration. Such drugs also have the potential to treat Alzheimer's disease and Parkinson's disease

© RUSSELL KIGHTLEY/SCIENCE PHOTO LIBRARY

HK97 bacteriophage capsid

HK97 bacteriophage capsid, molecular model. Bacteriophages are viruses that infect bacteria, in this case enterobacteria such as E. coli (Escherichia coli), with the phage head shown here. In viruses, the capsid is the protein shell that encloses the genetic material. A capsid consists of subunits called capsomeres that self-assemble to form the shell seen here. Here, this shell, approximately spherical in shape, has icosahedral symmetry. One of the functions of the capsid is to aid the transmission of the viral genetic material into host cells. The cell mechanisms are then used to produce new virus particles

© LAGUNA DESIGN/SCIENCE PHOTO LIBRARY