AP2A1 encodes the alpha-1 subunit of adaptor protein complex 2 (AP-2), a key component of clathrin-mediated endocytosis. This protein functions as a cargo adaptor that facilitates the internalization of membrane receptors and proteins by recognizing specific endocytic motifs and linking them to clathrin-coated vesicles 1 2. AP2A1 plays critical roles in receptor trafficking, including IGF-1 receptor endocytosis in keratinocytes, where it works complementarily with flotillin to mediate clathrin-dependent internalization 1. The protein also facilitates EGFR trafficking in lung adenocarcinoma cells, enhancing receptor endocytosis and recycling to promote oncogenic signaling 2. Beyond its canonical endocytic function, AP2A1 has been implicated in cellular senescence regulation, where its upregulation in senescent cells helps maintain enlarged cell architecture through integrin β1-mediated focal adhesion strengthening 3. In disease contexts, AP2A1 shows isoform-specific associations with neurofibrillary tangles in Alzheimer's disease 4 and serves as a predictor of alcohol use disorder severity in orbitofrontal cortex proteome analyses 5. Additionally, AP2A1 contributes to autophagy-mediated tight junction regulation through CLDN2 degradation pathways 6 and facilitates TGF-β signaling in pancreatic cancer progression 7.