Annexin II

Annexin II is a protein that in humans is encoded by the ANXA2 gene. It is a member of the annexin family of calcium-dependent phospholipid-binding proteins. Annexin II has a broad range of biological functions, playing an important role in cellular processes such as cellular signaling, inflammation, and cell growth and development. It is also implicated in the process of cellular differentiation and apoptosis. The protein is found in various tissues and cell types, often associated with the plasma membrane, where it participates in intracellular and extracellular signaling pathways.

Structure

Annexin II is a 36-kDa protein that forms a heterotetramer with another protein, p11 (S100A10), in the presence of calcium ions. This complex is often referred to as the annexin II complex. The structure of annexin II is characterized by a core domain containing four annexin repeats, which are responsible for the calcium-dependent phospholipid binding, and a unique N-terminal tail that mediates interactions with other proteins and cellular components.

Function

The functions of annexin II are diverse and include roles in the regulation of cell membrane dynamics, endocytosis, and exocytosis. It is also involved in the organization of the actin cytoskeleton, influencing cell shape, motility, and division. In addition, annexin II plays a critical role in the fibrinolysis system by acting as a receptor for plasminogen and tissue plasminogen activator (tPA), thereby facilitating the conversion of plasminogen to plasmin and contributing to the breakdown of fibrin clots.

Clinical Significance

Alterations in the expression and function of annexin II have been associated with various diseases, including cancer, cardiovascular diseases, and inflammatory disorders. In cancer, overexpression of annexin II has been observed in several types of tumors, where it is thought to contribute to tumor growth, invasion, and metastasis. Its role in angiogenesis and resistance to apoptosis also highlights its potential as a target for therapeutic intervention.

In cardiovascular diseases, annexin II has been implicated in the regulation of fibrinolysis, suggesting a role in the pathogenesis of thrombotic disorders. Its involvement in inflammatory responses also points to potential therapeutic applications in the treatment of inflammatory conditions.

Research Directions

Research on annexin II continues to uncover its complex roles in health and disease. Efforts are focused on elucidating the detailed mechanisms of its action in various cellular processes and pathological conditions. Understanding the multifaceted roles of annexin II could lead to the development of novel therapeutic strategies for a range of diseases.

Annexin II Resources
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