Updated project metadata. Amyloid beta 42 (Abeta42) is the principal trigger of neurodegeneration during Alzheimer’s disease (AD); however, the etiology of Abeta42 toxicity remains elusive. In a proteomic approach using a yeast model for intracellular Abeta42 toxicity, we here identify the HSP40 family member Ydj1, the yeast orthologue of human DnaJA1, as a crucial factor in Abeta42-mediated toxicity.