Blog – What’s in a name? Amyloid, Amyloid-beta, Beta Amyloid, Amy-Lloyd
When I was a PhD student, I attended a conference where a very senior colleague, Prof. Mark Pepys, spoke about the definition of amyloid and his words stayed with me. He was adamant about the importance of precise language in describing science. Since then, the amyloid nomenclature committee has worked through several iterations, updating the definition to incorporate intracellular and functional amyloid. The number of officially recognised amyloid precursor proteins now stands at 42 — and is still growing.
The amyloid nomenclature committee (2022) agreed that “the term ‘amyloid fibril’ should be used for any cross β-sheet fibril”, and that the precursor protein and its origin should always be named. Reference
Given how broad the definition of amyloid has become — encompassing many different protein compositions — why do we still use the word “amyloid” alone when referring to amyloid-beta protein, its fibrils, and the plaques deposited in Alzheimer’s brains?
Amyloid describes a structure: a self-assembled protein. It covers multiple proteins that misfold and form fibrils and filaments. Tau forms amyloid – Paired helical filaments are amyloid. Insulin can form amyloid at high concentrations. Antibodies — immunoglobulin light and heavy chains — can form amyloid and deposit in the heart and skin. These are all diseases of protein misfolding, each characterised by a specific protein (or proteins), and each sharing the defining feature of a beta-sheet-rich fibril structure. Historically, diagnostic criteria included Congo red staining, which highlights amyloid deposits in blood vessels and organs with a distinctive green colour under a cross-polarising microscope.
Perhaps even more striking is that amyloid can be functional. Bacteria such as E. coli use amyloid fibrils — assembled from a family of related proteins called curli (CSGs) — for adhesion and protection. Amyloid fibrils are also found in sperm, play roles in viral infection and immune response, and even form the structural basis of lacewing egg silk stalks. This last example underlines the inherent stability and strength of the amyloid structure.
Why does the word matter? Surely, we all know what we mean?
I would argue that words matter enormously. Precision in language is critical — especially when we are communicating with the public, with those developing new therapies, or with those who fund our research.
Consider an analogy: imagine using the word “people” to describe the actions of a specific world leader. “People have passed a law giving everyone the freedom to fly.” The name of the leader matters. Their country matters. Their specific characteristics matter. In the same way, the amino acid sequence of amyloid-beta is precisely what gives it its name. Its chemical characteristics determine its structure, its function, and its biological behaviour — including how it folds, or misfolds. We cannot use a word that groups everything together, any more than we should generalise across all humans or entire populations.
So here is my plea. Please use the term amyloid-beta when describing Alzheimer’s disease and its pathologies. Using “amyloid” alone risks confuses those we communicate with — and, in doing so, risks confusing ourselves.
Professor Louise Serpell
Author
Professor Louise Serpell is an Emerita Professor of Biochemistry at the University of Sussex. Her research focuses on how proteins misfold and form amyloid structures linked to Alzheimer’s disease and other neurodegenerative conditions, using approaches from structural biology and molecular biophysics. Louise completed her DPhil at the University of Oxford and later established her own research group in the UK. Alongside her research career, she has been active in mentoring, public engagement, and supporting early career researchers.