Here, we demonstratethat the most ubiquitous peptidyl prolyl isomerase, peptidyl prolylisomerase A (PPIA), concentrates inside liquid-like droplets formedby the Alzheimer’s disease-associated protein tau, as wellas inside RNA-induced coacervates of a proline–arginine dipeptiderepeat protein. The gene discussed is PPIA; the disease is early-onset autosomal dominant Alzheimer disease.