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A modified host protein model of scrapie
1Department of Molecular Biology, New York State Office of Mental Retardation and Developmental Disabilities, Staten Island 10314.
Ciba Foundation Symposium
|January 1, 1988
Summary
The scrapie agent, a protein called Sp33-37, is a modified host protein that causes disease. This abnormal protein accumulates and spreads, potentially initiating scrapie or similar neurological disorders.
Area of Science:
- Neuroscience
- Biochemistry
- Molecular Biology
Background:
- The scrapie agent's biochemical and ultrastructural properties remain incompletely understood.
- A functional protein component is essential for scrapie agent activity.
- Scrapie agent purification involves proteinase K digestion, yielding PrP 27-30.
Purpose of the Study:
- To propose a model for the scrapie agent's composition and replication mechanism.
- To investigate the role of host-derived proteins in scrapie pathogenesis.
- To challenge the notion of a non-host nucleic acid being part of the scrapie agent.
Main Methods:
- Isolation and characterization of protein components from scrapie-affected brain tissue.
- Comparison of proteins obtained with and without protease digestion.
- Biochemical analysis to determine protein mass and origin.
Main Results:
- A 33-37 kDa glycoprotein (Sp33-37) is the major protein in non-digested scrapie brain isolates.
- Sp33-37 is a larger form of PrP 27-30 and originates from a normal host gene.
- The study suggests Sp33-37, a modified host protein, is the critical component of the scrapie agent.
Conclusions:
- A modified host protein (Sp33-37) is proposed as the critical component of the scrapie agent, not a non-host nucleic acid.
- Sp33-37 may induce disease and self-replication by acting on normal host proteins.
- Replication involves substrate availability, aggregate formation, and cell-to-cell spread, potentially initiated by metabolic errors.