Phosphoglycerate kinase 1 cooperates with the AP2 complex to promote endocytosis.

Adaptor proteins play a critical role in intracellular protein transport by binding to cargoes and facilitating their sorting into vesicles. The adaptor protein 2 (AP2) complex specifically recognizes sorting motifs on cargo proteins such as epidermal growth factor receptor (EGFR) and transferrin receptor (TfR) for proper cargo recognition. However, the coordination of adaptor proteins in cargo recognition remains unclear. Here, we uncover the non-canonical role of glycolytic enzyme phosphoglycerate kinase 1 (PGK1) in protein endocytosis, acting independently of its catalytic activity. PGK1 serves as a co-adaptor to directly engage cargoes and reinforce AP2 complex stability, orchestrating efficient cargo recognition to promote endocytosis. Furthermore, PGK1 also integrates into the AP2-clathrin complex, enhancing cargo recognition and internalization. Collectively, our findings establish a previously unidentified coat protein complex containing PGK1, highlighting its dual role as a cargo adaptor and stabilizer of the AP2 complex.