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Molecular cloning of a candidate chicken prion protein
J M Gabriel1, B Oesch, H Kretzschmar
1Department of Neurology, University of California, San Francisco 94143.
Abstract:
Fractions enriched for acetylcholine receptor-inducing activity from chicken brain were found to contain a protein that was approximately 30% homologous with mammalian prion proteins [Harris, D. A., Falls, D. L., Johnson, F. A. & Fischbach, G. D. (1991) Proc. Natl. Acad. Sci. USA 88, 7664-7668]. To extend these observations, we recovered genomic clones encoding a putative chicken prion protein (PrP). Like mammalian PrP molecules, the candidate chicken PrP is encoded by a single-copy gene and the entire open reading frame is found within a single exon. All of the structural features of mammalian PrP were found in the chicken protein. When the N-terminal repeats of PrP were not considered, the chicken and mammalian proteins were approximately 55% homologous, allowing for conservative substitutions. Screening of a chicken genomic DNA library failed to identify a more closely related chicken PrP homologue. These findings argue that the protein which purifies with acetylcholine receptor-inducing activity is chicken PrP.
Insights
Researchers identified a chicken prion protein (PrP) homologous to mammalian PrP. This chicken PrP is the protein responsible for acetylcholine receptor-inducing activity found in chicken brain extracts.
Area of Science:
- Neuroscience
- Molecular Biology
- Protein Chemistry
Background:
- Fractions from chicken brain with acetylcholine receptor-inducing activity contained a protein homologous to mammalian prion proteins.
- Previous research indicated a partial homology (30%) between this protein and mammalian prion proteins.
Purpose of the Study:
- To isolate and characterize genomic clones encoding a putative chicken prion protein (PrP).
- To determine if this chicken PrP is the protein responsible for acetylcholine receptor-inducing activity.
Main Methods:
- Recovery of genomic clones encoding chicken PrP.
- Analysis of gene structure and protein homology with mammalian PrP.
- Screening of a chicken genomic DNA library for related homologues.
Main Results:
- A candidate chicken PrP was identified, encoded by a single-copy gene with its open reading frame in a single exon.
- The chicken PrP shares structural features with mammalian PrP, exhibiting approximately 55% homology (excluding N-terminal repeats).
- No more closely related chicken PrP homologues were found in the genomic library screening.
Conclusions:
- The identified chicken PrP possesses structural and sequence similarities to mammalian PrP.
- These findings strongly suggest that the protein associated with acetylcholine receptor-inducing activity in chicken brain is indeed chicken PrP.