A plausible function of the prion protein: conjectures and a hypothesis

Area of Science:

• Neurobiology
• Molecular Biology
• Biochemistry

Background:

• Amyloid precursor protein (APP) and prion protein (PrP) are cell membrane proteins linked to neurodegenerative diseases.
• Both APP and PrP undergo endoproteolysis, a process involving cleavage within the protein.
• Existing literature suggests potential relationships between APP and PrP, including overlapping functions and coinciding cellular distributions.

Purpose of the Study:

• To propose a novel mechanism for the interaction between prion protein (PrP) and amyloid precursor protein (APP).
• To elucidate the potential role of PrP in the cleavage of APP.
• To explain certain characteristics of spongiform encephalopathies through this proposed interaction.

Main Methods:

• Literature review and synthesis of existing evidence.
• Hypothetical modeling of protein-protein interactions and enzymatic activity.
• Theoretical explanation of disease mechanisms based on proposed molecular interactions.

Main Results:

• It is proposed that PrP catalyzes its own cleavage.
• The C-terminal fragment of PrP is hypothesized to function as an alpha secretase.
• The N-terminal segment of PrP may act as a chaperone for the active site.

Conclusions:

• The proposed alpha secretase activity of PrP releases anticoagulant and neurotrophic ectodomains from APP.
• This model offers a potential explanation for specific features observed in spongiform encephalopathies.
• The study highlights a potential link between PrP function and APP processing in neurodegeneration.