ANXA5

ANXA5 Full Name

annexin A5

ANXA5 Introduction

Annexin A5 (ANXA5), also commonly known as Annexin V, is a calcium-dependent phospholipid-binding protein belonging to the highly conserved annexin superfamily. The ANXA5 gene is widely expressed in a variety of human tissues and cells, with abundant expression in vascular endothelial cells, placental trophoblasts, cardiomyocytes and immune cells. Functionally, ANXA5 preferentially binds to phosphatidylserine exposed on the outer membrane leaflet during cell apoptosis, membrane damage and cellular stress responses. It participates in the regulation of membrane stabilization, anti-inflammatory reactions, anticoagulation, cellular apoptosis modulation and placental physiological maintenance. As an evolutionarily conserved gene, ANXA5 maintains critical physiological homeostasis, and its abnormal expression or genetic variation is closely linked to multiple human diseases, making it a widely used molecular biomarker and research tool in cell biology, diagnostics and translational medicine.

Figure 1. Schematic structure of Annexin A5.

Gene and Protein Characteristics
ANXA5 is located on human chromosome 4q27, encoding a single major isoform of approximately 36 kDa protein. The typical structural feature of ANXA5 is the presence of four conserved annexin repeat domains, which endow the protein with calcium ion coordination and phospholipid membrane binding capacity. Unlike many other annexin family members, ANXA5 exhibits high affinity and reversible binding to negatively charged membrane phospholipids in a calcium-dependent manner, without requiring additional cofactors for membrane association. Its molecular structure enables it to form two-dimensional crystalline arrays on damaged cell membranes, further protecting membrane integrity and inhibiting excessive inflammatory and coagulation cascades.

Biological Functions

ANXA5 plays multifaceted biological roles in physiological and pathological processes. It serves as a classic marker for detecting early cell apoptosis due to its specific binding ability to externalized phosphatidylserine. In the cardiovascular system, ANXA5 exerts potent anticoagulant and antithrombotic effects by competing with coagulation factors for phospholipid binding sites on damaged vascular endothelium. In reproductive biology, ANXA5 is highly expressed in the placenta and contributes to maintaining normal trophoblast function, embryonic development and maternal-fetal immune tolerance. Additionally, ANXA5 participates in the regulation of cell proliferation, oxidative stress response, and immune cell activation, acting as a key modulator linking membrane physiology, inflammation and tissue repair.

Alternate Names for ANXA5

ANXA5; annexin A5; PP4; ANX5; ENX2; RPRGL3; HEL-S-7; CBP-I; PAP-I; VAC-alpha