Martinsried. Researchers discovered that prions, which are naturally occurring protein clumps in yeast, are involved in the toxicity of the disease-related protein Huntingtin. They found that the actual toxic form of the Huntingtin protein is not large aggregates, as previously suspected, but smaller intermediates, so-called oligomers. Those intermediates arise through specific interactions with prions. The researchers now suspect similar relationships in human disease. The study was published in the journal Molecular Cell and is an achievement of the team led by Ulrich Hartl at the Max Planck Institute of Biochemistry (MPIB).