Alzheimer’s-affected brains are riddled with so-called amyloid plaques: protein aggregates consisting mainly of amyloid-beta. However, this amyloid-beta is a fragment produced from a precursor protein whose normal function has remained enigmatic for decades. A team of scientists has now uncovered that this amyloid precursor protein modulates neuronal signal transmission through binding to a specific receptor. Modulating this receptor could potentially help treat Alzheimer’s or other brain diseases.