Prion

Prion is compounded of protein & infection. They have a distinct extracellular form, but the extracellular form seems to be entirely protein. It apparently does not contain any nuleic acid, or if it does, the molecule is not long enough to encode the single kind of protein of wich the prion is composed. These bits are detected by Stanly Procini in 1982. Prion has been discovered that the host cell contains a gene on one of its chromosomes that encodes a prion very similar to the prion protein. The host protein is normally produced and is found mostly in neurons. Apparently, the incoming prion modifies this host protein either during or after synthesis. The modi-fication involves an alternative pattern of folding and causes the protein to lose its normal function, to become partially resistant to proteases, and to become insoluble. Normal protein prion has an alpha helix structure. When these proteins change to beta plate,collected as strings in neurons and disorder their functions and even-tually cause death of these cells. The fatal effect of prions cause forming spongiosa tissue in brain by composing holes in it. The prion protein particle is infectious, and various prions are known to cause a variety of diseases in animals, such as scrapie in sheep, bovine spongiform encephalopathy in cattle (BSE or mad cow disease ), and Kuru and Cruetzfeldt-Jakob disease (CJD) in humans. Todays a number of scientists consider that the cause of Alzhimer and Parkinson is also prions. There are a lot of doubts about prions, their pathogens and transmitting. There is hope of answering to more questions about them in future. Aim of this article is assessment of normal and abnormal prion protein specifics and their effects to nervous system operation and abnormalities incidence

کلیدواژه ها:

prion ، prion protein ، spong tissue ، mad cow disease