Editing Prion (section)

==== PrP<sup>res</sup> ====
Protease-resistant PrP<sup>Sc</sup>-like protein (PrP<sup>res</sup>) is the name given to any isoform of PrP<sup>c</sup> which is structurally altered and converted into a misfolded [[proteinase K]]-resistant form.<ref>{{cite journal | vauthors = Riesner D | title = Biochemistry and structure of PrP(C) and PrP(Sc) | journal = British Medical Bulletin | volume = 66 | issue = 1 | pages = 21–33 | date = June 2003 | pmid = 14522846 | doi = 10.1093/bmb/66.1.21 | doi-access = free }}</ref> To model conversion of PrP<sup>C</sup> to PrP<sup>Sc</sup> ''in vitro'', Kocisko ''et al''. showed that PrP<sup>Sc</sup> could cause PrP<sup>C</sup> to convert to PrP<sup>res</sup> under cell-free conditions <ref name="pmid7913989">{{cite journal | vauthors = Kocisko DA, Come JH, Priola SA, Chesebro B, Raymond GJ, Lansbury PT, Caughey B | title = Cell-free formation of protease-resistant prion protein | journal = Nature | volume = 370 | issue = 6489 | pages = 471–4 | date = August 1994 | pmid = 7913989 | doi = 10.1038/370471a0 | bibcode = 1994Natur.370..471K | hdl-access = free | s2cid = 4337709 | hdl = 1721.1/42578 }}</ref> and Soto ''et al''. demonstrated sustained amplification of PrP<sup>res</sup> and prion infectivity by a procedure involving [[Protein misfolding cyclic amplification|cyclic amplification of protein misfolding]].<ref name="pmid11459061">{{cite journal | vauthors = Saborio GP, Permanne B, Soto C | title = Sensitive detection of pathological prion protein by cyclic amplification of protein misfolding | journal = Nature | volume = 411 | issue = 6839 | pages = 810–3 | date = June 2001 | pmid = 11459061 | doi = 10.1038/35081095 | bibcode = 2001Natur.411..810S | s2cid = 4317585 }}</ref> The term "PrP<sup>res</sup>" may refer either to protease-resistant forms of PrP<sup>Sc</sup>, which is isolated from infectious tissue and associated with the transmissible spongiform encephalopathy agent, or to other protease-resistant forms of PrP that, for example, might be generated ''in vitro''.<ref name="pmid15297610">{{cite journal | vauthors = Bieschke J, Weber P, Sarafoff N, Beekes M, Giese A, Kretzschmar H | title = Autocatalytic self-propagation of misfolded prion protein | journal = Proceedings of the National Academy of Sciences of the United States of America | volume = 101 | issue = 33 | pages = 12207–11 | date = August 2004 | pmid = 15297610 | pmc = 514458 | doi = 10.1073/pnas.0404650101 | bibcode = 2004PNAS..10112207B | doi-access = free }}</ref> Accordingly, unlike PrP<sup>Sc</sup>, PrP<sup>res</sup> may not necessarily be infectious.

[[File:Prion structure membrane bound fibril.jpg|thumb|Models of normal (PrP<sup>C</sup>) and infectious (PrP<sup>Sc</sup>) forms of prion protein on a membrane: polypeptide (turquoise); glycans (red); glycolipid anchors (blue). The core structures are based on NMR spectroscopy (PrP<sup>C</sup>) and cryo-electron microscopy (PrP<sup>Sc</sup>).]]