Final answer:
The pathogenic prion protein, or PrPSc, is a misfolded form of the normal cellular protein, which causes brain lesions and is associated with transmissible spongiform encephalopathies. It resists proteolysis and can induce misfolding in normal proteins, leading to myriad neurological symptoms and eventual death.
Step-by-step explanation:
Features of Pathogenic Prion Protein
The pathogenic prion protein, often denoted as PrPSc, is a misfolded variant of the normal cellular prion protein (PrPC). This misfolded prion can arise spontaneously in brain tissue, particularly in the presence of mutant proteins, or through consumption of infected food. The infectious PrPSc binds to the normal PrPC and converts it into more PrPSc, leading to an exponential increase in the disease-causing proteins which aggregate and cause brain lesions. This abnormal folding largely consists of β-pleated sheets, which makes the protein resistant to proteolysis and capable of inducing further misfolding of normal PrPC into PrPSc. Infected brain tissue is characterized by a spongy appearance due to the formation of vacuoles.
Prions are unique as they are an infectious agent not reliant upon nucleic acids, thus representing a novel category of disease-causing entities. They are associated with causing various forms of transmissible spongiform encephalopathies (TSEs), such as mad cow disease (BSE) and kuru, characterized by the accumulation of PrPSc and resulting in severe neurological symptoms and death.
Recent studies suggest that normal prion proteins (PrPC) might have roles such as memory formation, which are disrupted when they misfold into amyloid plaques, a hallmark of neurodegenerative diseases.