AnxA6

AnxA6 (Annexin A6) is a Ca²⁺-dependent phospholipid-binding protein that functions as a multifunctional scaffold coordinating membrane trafficking, signal transduction, and cellular homeostasis^[1][2]. Unlike most annexin family members that contain four annexin repeats, AnxA6 is the largest annexin and possesses eight conserved annexin repeats, providing a distinctive structural basis for its scaffolding and membrane-associated functions^[3]. Mechanistically, AnxA6 participates in the endocytic pathway by organizing signaling complexes that regulate receptor trafficking and intracellular signaling^[1]. AnxA6 recruits PKCα and p120GAP, thereby suppressing EGFR/Ras/MAPK signaling and promoting lysosomal targeting of EGFR, linking membrane trafficking to growth factor signal regulation^[1][4]. In addition, AnxA6 controls cholesterol homeostasis through late endosome-lysosome and endoplasmic reticulum membrane-contact mechanisms, influencing caveolae formation, integrin recycling, and membrane transport processes^[1][2]. These activities connect AnxA6 to fundamental cellular processes including membrane remodeling, cytoskeletal regulation, and vesicular transport^[2]. In disease-related settings, altered AnxA6 expression has been associated with cancer progression and diverse pathological states, where it may exert either tumor-suppressive or tumor-promoting effects depending on biological context^[2][5]. Furthermore, AnxA6 is a major component of matrix vesicles involved in extracellular matrix mineralization, Ca²⁺ transport, and hydroxyapatite formation, supporting its use in studies of osteoporosis, osteoarthritis, vascular calcification, and related mineralization disorders^[6]. Currently, no widely established selective AnxA6 agonists or inhibitors are routinely used, and experimental research primarily relies on genetic or expression-based modulation approaches^[6].