Prion protein, also known as PRNP, is a ubiquitous membrane glycoprotein whose abnormal self-replicating, misfolded form is widely believed to cause several central nervous system disorders, collectively known as Transmissible Spongiform Encephalopathies (TSE). This protein contains a highly unstable region of five tandem octapeptide repeat. Mutations in the repeat region as well as elsewhere in this gene have been associated with Creutzfeldt-Jakob disease, fatal familial insomnia, Gerstmann-Straussler disease, Huntington disease-like 1, and kuru. Recombinant human PRNP protein, fused to His-tag at N-terminus, was expressed in E.coli.