Pathway

Biosynthesis of A2E, implicated in retinal degradation

Lipofuscin is a yellow-brown pigment grain composed mainly of lipids but also sugars and certain metals. Accumulation of lipofuscin is associated with degenerative diseases such as Alzheimer's disease, Parkinson's disease, chronic obstructive pulmonary disease and retinal macular degeneration.

A prominent component of lipofuscin in retinal pigment epithelial (RPE) cells is the bisretinoid A2E (di-retinoid-pyridinium-ethanolamine), the end-product of the condensation of 2 molecules of all-trans-retinal (atRAL) and phosphatidylethanolamine (PE) in photoreceptor outer disc membranes. Once formed, A2E is phagocytosed, together with outer segments, to RPE where it accumulates. There is no evidence as yet to indicate that A2E can be catabolised. A simplified biosynthetic pathway for A2E is described here.

Summary from Reactome (R-HSA-2466712), read 2026-09-23.

REACT:R-HSA-2466712Reactome

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What the reference databases state

Statements

1 statement

1 statement · 1 reference database · Subject: Biosynthesis of A2E, implicated in retinal degradation · Sources: Reactome

Order

NAPEPLD participates in Biosynthesis of A2E, implicated in retinal degradationProteinReactome R-HSA-2466712Inferred only