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Research on the effects of exposure of micro-organisms to high hydrostatic pressure (HHP) has grown in the last decade. The main foci have been to understand adaptation to life in the deep ocean and the HHP stress response. Amongst other effects, HHP interferes with the cellular membrane structure, increasing the order of lipid molecules espe-cially in the vicinity of proteins, leading to decreased membrane fluidity. Protein structure may also be affected by pres-sure, disturbing polymerization, folding and the activity. HHP also inhibits protein synthesis, one of the most piezosensi-tive cellular functions. Ribosome disassembly contributes to this inhibition. RNA synthesis is maintained at pressures at which DNA and protein synthesis are completely inhibited. A number of these responses overlap with responses to other forms of stress, particularly cold stress. Microarray analysis of micro-organisms has identified numerous genes up-regulated after exposure to high pressure. However, many of these genes code for proteins of unknown function. Corre-sponding proteomic analyses detect very few proteins synthesized as a result of such exposure. The review high lights the need for future research to understand the complex pathways involved in the response to HHP.

High hydrostatic pressure (HHP) is a powerful tool to study protein folding and the dynamics and structure of folding intermediates. Aggregates and amyloids, derived from partially folding intermediates at the junction between productive and off-pathway folding, have been studied as well, which promises better understanding of the protein misfolding diseases. Here is summarized the recent data we have collected with transthyretin under pressure.