AP-2 complex subunit alpha-1

AP-2 complex subunit alpha-1 (AP2A1) is a core component of the adaptor protein complex 2 (AP-2), which mediates clathrin-dependent endocytosis and cargo selection at the plasma membrane (UniProt: O95782). The protein's alpha subunit binds polyphosphoinositide lipids and serves as a scaffolding platform through its C-terminal appendage domain, facilitating the recognition of endocytic signal motifs on cargo molecules. AP-2 is particularly important in synaptic function, including synaptic vesicle membrane recycling and the endocytosis of membrane proteins during long-term potentiation.

AP2A1 is widely expressed across tissues and functions primarily in membrane trafficking pathways essential for cellular homeostasis. No UniProt-curated disease associations are documented for this protein.

In Alzheimer's disease, AP2A1 is consistently down-regulated in post-mortem human AD brain tissue compared to age-matched controls (Chaparral AD proteomics; mean log2 fold-change: −0.48). This reduction in AP-2 complex abundance may impair clathrin-mediated endocytosis and synaptic vesicle dynamics, potentially contributing to the synaptic dysfunction characteristic of AD pathology.