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A prion / ˈ p r iː ɒ n / ⓘ is a misfolded protein that induces misfolding in normal variants of the same protein, leading to cellular death.Prions are responsible for prion diseases, known as transmissible spongiform encephalopathy (TSEs), which are fatal and transmissible neurodegenerative diseases affecting both humans and animals.
Infectious prions are misfolded proteins that can cause normally folded proteins to also become misfolded. [4] About 85% of cases of CJD occur for unknown reasons, while about 7.5% of cases are inherited in an autosomal dominant manner. [4] [9] Exposure to brain or spinal tissue from an infected person may also result in spread. [4]
The infectious agent is a misfolded form of a host-encoded protein called prion (PrP). Prion proteins are encoded by the Prion Protein Gene . [22] The two forms of prion are designated as PrP c, which is a normally folded protein, and PrP sc, a misfolded form which gives rise to the disease.
The subsequent demonstration that human prion diseases were transmissible reinforced the importance of spongiform change as a diagnostic feature, reflected in the use of the term "spongiform encephalopathy" for this group of disorders. Prions appear to be most infectious when in direct contact with affected tissues.
Infected cervids do this, but humans with prion disease have never been known to do so. The finding could mean that humans with CWD pass infectious prions in their fecal matter, according to Hannaoui.
In medicine, proteinopathy ([pref. protein]; -pathy [suff. disease]; proteinopathies pl.; proteinopathic adj), or proteopathy, protein conformational disorder, or protein misfolding disease, is a class of diseases in which certain proteins become structurally abnormal, and thereby disrupt the function of cells, tissues and organs of the body.
The abnormal protein PrP Sc accumulates in the brain and destroys nerve cells, which leads to the mental and behavioral features of prion diseases. [citation needed] Several other changes in the PRNP gene (called polymorphisms) do not cause prion diseases but may affect a person's risk of developing these diseases or alter the course of the ...
Misfolded proteins can form protein aggregates or amyloid fibrils, get degraded, or refold back to its native structure. In molecular biology, protein aggregation is a phenomenon in which intrinsically-disordered or mis-folded proteins aggregate (i.e., accumulate and clump together) either intra- or extracellularly.