Schematic diagram of the nuclear magnetic resonance-derived structure, posttranslational modifications of human PrPC, and epitopes of anti-PrP antibodies. Schematic diagram of the nuclear magnetic resonance-derived structure, posttranslational modifications of human PrPC, and epitopes of anti-PrP antibodies. Mature human PrP contains 209 amino acids. It consists of a flexible N-terminal domain containing four copper-binding octapeptide repeats and a folded C-terminal domain containing two β-sheets and three α-helical structures. The cysteines at positions 179 and 214 form a disulfide bond between the α2 and α3 domains. Two N-linked glycosylation sites are at residues 181 and 197, and the GPI anchor is linked to residue 231. The epitopes of anti-PrP antibodies 1E4 and 3F4 are located at residues 97 to 105 and 106 to 112, respectively. Alvin S. Das, and Wen-Quan Zou Clin. Microbiol. Rev. 2016; doi:10.1128/CMR.00046-15