Prion diseases such as Creutzfeldt-Jakob disease involve conversion of a normally expressed cellular protein into an infectious isoform. At the level of protein structure, this conversion is best described as:

• A Proteolytic truncation of PrPC generating a smaller amyloidogenic fragment
• B A point mutation in the PRNP gene that replaces glycine with valine, permitting polymerization
• C A post-translational conformational change in which the alpha-helix-rich PrPC refolds into a beta-sheet-rich, protease-resistant PrPSc ✓
• D Non-enzymatic glycation of PrPC that cross-links adjacent molecules into insoluble fibrils

Explanation

PrPC is a normal membrane glycoprotein rich in alpha helix. In prion disease it refolds into PrPSc, a beta-sheet-rich conformer that is relatively protease-resistant and templates further conversion of PrPC, propagating without any change in amino acid sequence. While PRNP mutations can predispose to familial disease, the infectious conversion itself is purely conformational, and glycation plays no role.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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