Active accumulation of the data on new amyloids continuing nowadays dissolves boundaries of the term “amyloid”. Currently, it is most often used to designate aggregates with cross-β structure. At the same time, amyloids also exhibit a number of other unusual properties, such as: detergent and protease resistance, interaction with specific dyes, and ability to induce transition of some proteins from a soluble form to an aggregated one. The same features have been also demonstrated for the aggregates lacking cross-β structure, which are commonly called “amyloid-like” and combined into one group, although they are very diverse. We have collected and systematized information on the properties of more than two hundred known amyloids and amyloid-like proteins with emphasis on conflicting examples. In particular, a number of proteins in membraneless organelles form aggregates with cross-β structure that are morphologically indistinguishable from the other amyloids, but they can be dissolved in the presence of detergents, which is not typical for amyloids. Such paradoxes signify the need to clarify the existing definition of the term amyloid. On the other hand, the demonstrated structural diversity of the amyloid-like aggregates shows the necessity of their classification.

The study of the SUP45 and SUP35 genes of yeast Saccharomyces cerevisiae in the laboratory of Physiological Genetics of St. Petersburg State University began in 1964 when the first omnipotent nonsense suppressor mutations were obtained. During the following 55 years, a lot of information about these genes has been gained through the research efforts of various laboratories. Now we know that SUP45 and SUP35 encode translation termination factors eRF1 and eRF3, respectively. Both genes are essential, and sup45 and sup35 mutations lead not only to impaired translation but also to multiple pleiotropic effects. The aim of this review is to summarize known data about suppressor mutations in SUP45 or SUP35 genes.

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The number of yeast prions and prion-like proteins described since 1994 has grown from two to nearly twenty. If in the early years most scientists working with the classic mammalian prion, PrPSc, were skeptical about the possibility of using the term prion to refer to yeast cytoplasmic elements with unusual properties, it is now clear that prion-like phenomena are widespread and that yeast can serve as a convenient model for studying them. Here we give a brief overview of the yeast prions discovered so far and focus our attention to the various approaches used to identify them. The prospects for the discovery of new yeast prions are also discussed.