Topic > Prion Protein Essay - 997

Prion proteins are small infectious particles formed by the misfolding of the protein structure. Failure to fold such proteins is believed to have been the cause of diseases such as bovine spongiform encephalopathy in cows and Creutzfeldt-Jakob disease in humans. The prion proteins known to humanity so far suggest that they affect the brain of the affected individual. “A study1 published in the British Medical Journal reveals that 1 in 2,000 people in the UK may harbor the infectious prion protein that causes variant Creutzfeldt-Jakob disease (vCJD)” (Callaway, 2013). The study therefore shows that a large number of people are at risk and this is cause for concern as the prion protein that is folded incorrectly causes normal proteins in the brain to alter their structure so that they too are folded incorrectly. The missing structure is thought to be very stable, and as levels of the protein build up within the infected tissue, this causes destruction and ultimately death of the cell. The prion protein PrP is believed to be the cause of all mammalian prion diseases, but the structure of the protein has yet to be discovered. The normal cellular form of the prion protein is PrPc, while the missfolded scrapie form is PrPSc. PrPc is made up of 209 amino acids and one disulfide bond and is found on cell membranes. “There are different topological forms; a cell surface form anchored by glycolipid and two transmembrane forms.” (Hedge et al, 1998). The missfolded form, PrPSc, has multiple Beta sheets, however the normal form PrPc has some Alpha structure present. “Fourier transform infrared spectroscopy (FTIR) demonstrated that PrPC has a high alpha-helix content (42%) and no beta-sheet (3%), results that were c...... halfway through paper.... ..and N-terminal domain converting it into a helical structure.” (Muira et al, 1996). Binding of copper to the prion has many effects higher copper uptake than mice that did not have PrP. Furthermore, other research has found that the binding of copper to the prion protein prevents unusual interactions with other proteins such as plasminogen PrP has a protective effect. Investigations have shown that if copper absorption is disturbed, this can cause long-term potentiation. "The imbalance in synaptic Cu causes disturbances in the activity of receptors such as GABA receptors and impairs potentiation long term." (Gabrielsson et al 1986; Vlachova et al, 1996). One experiment found that if cells were exposed to copper, this would result in an increased rate of uptake.