Chapter 5 – Prions and Prion-Like Phenomena in Epigenetic Inheritance

At the time that the concept of gene as a stretch of DNA encoding a function was not fully established, several models proposed that regulatory networks or macromolecular structures could also generate hereditary traits. Long forgotten, this kind of epigenetic inheritance has been revived by the discovery that some non-mendelian inheritance in the yeast Saccharomyces cerevisiae is due to proteins able to switch their structure in an autocatalytic manner, now called prion. We review here what we know about these cellular prions; and also about additional phenomena, which in their genetic determinism resemble prions, however, based on alternative states of macromolecular complexes or regulatory networks.