Definitions by theprionthey

PrPSc

PrPSc is a misfolded isoform of the healthy human prion protein, PrPC, responsible for all known transmissible spongiform encephalopathies. The "Sc" in its name stands for "scrapie", which is the neurodegenerative disease where PrPSc was first identified. When in its healthy isoform, PrP is an alpha-helix-rich glycoprotein found on the cell membranes of neurons. It performs a multitude of functions in the brain, such as preventing Bax-induced apoptosis, lowering oxidative stress on neurons, assisting in enzyme catalysis through copper binding, performing transmembrane signaling, assisting with synaptic formation and communication, and helping with neuronal and glial cell adhesion. However, when PrPC misfolds into this pathogenic isoform, it is instead rich in beta-pleated sheets. It forms a large structure known as a beta-solenoid, which then aggregates into large amyloid fibrils attached to the surface of neurons. The primary cause of synaptotoxicity and neurodegeneration in TSEs is membrane-anchored PrPSc, which causes damage through NMDA receptor-mediated influx of Ca2+ ions upon binding with PrPC, activation of the inflammatory protein p38 MAPK, and the collapse of the cell's actin cytoskeleton. The pathogenicity of PrPSc comes from its extremely dense core's resistance to proteases and its ability to template itself onto normal PrPC molecules. All transmissible spongiform encephalopathies are invariably fatal, and cause the brain to appear sponge-like.

Guy: "dude mad cow is genuinely terrifying"
Other guy: "yeah same with everything caused by PrPSc really"

PrPSc by theprionthey October 4, 2026