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What is a Prion?

In its normal state, prion protein (PrPC, the C stands for “Cellular”) is a cell surface glycoprotein present in most mammalian tissues (1). Its function is not fully determined but evidence suggests it plays a role in metal homeostasis as it binds copper ions (2). However, it can accumulate in abnormal forms that cause neurodegenarative disorders known as transmissible spongiform encephalopathies (TSE), such as BSE, scrapie and CJD. As well as the accumulation of abnormal PrP, a key feature of TSEs is their transmissibility. The nature of the infectious agent is undetermined, but is thought to be the abnormal form of PrPC, which is known as PrPres, because, unlike its normal cellular counterpart it is partially resistant to protease degradation (3). The abnormal form is also sometimes referred to as PrPSc (scrapie). It has been proposed that that the abnormal form is infectious because it has the ability to convert normal PrPC in healthy individuals into the abnormal form.

References

1. Caughey, B. (2001). Interactions between prion protein isoforms: the kiss of death? Trends Biochem. Sci., 26: 235-242

2. Martins, V. R., Mercadante, A. F., Cabral, A. L. B., Freitas, A. R. O. and Castro, R. M. R. P. S. (2001). Insights into the physiological function of cellular prion protein. Brazilian J. Med. Biol. Res., 34: 585-595.

3. Prusiner, S. B. (1998). Prions. Proc. Natl. Acad. Sci., USA

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What is a Prion?

References