|Annexin A1 in Human Breast. Annexin A1 was detected in immersion fixed paraffin-embedded sections of human breast using Mouse Anti-Human Annexin A1 Monoclonal Antibody (Catalog # MAB3770) at 15 µg/mL overnight at 4 °C. Before incubation with the primary antibody, tissue was subjected to heat-induced epitope retrieval using Antigen Retrieval Reagent-Basic (Catalog # CTS013). Tissue was stained using the Anti-Mouse HRP-DAB Cell & Tissue Staining Kit (brown; Catalog # CTS002) and counterstained with hematoxylin (blue). Specific staining was localized to myoepithelial cells. View our protocol for Chromogenic IHC Staining of Paraffin-embedded Tissue Sections.|
The Annexins are a family of Calcium-dependent phospholipid-binding proteins that are preferentially located on the cytosolic face of the plasma membrane. The Annexin’s have a molecular weight of approximately 35 to 40 kDa and consist of a unique amino terminal domain followed by a homologous C-terminal core domain containing the calcium-dependent phospholipid-binding sites. The C‑terminal domain is comprised of four 60‑70 amino acid repeats, known as annexin repeats or an endonexin fold (Annexin A6 contains 8 annexin repeats). The four annexin repeats form a highly alpha -helical, tightly packed disc known as the annexin domain, which binds to phospholipids in the membrane in a calcium-dependent manner. Members of the annexin family play a role in cytoskeletal interactions, phospholipase inhibition, regulation of cellular growth, and intracellular signal transduction pathways. Annexin A1 (ANXA1), also known as annexin I, lipocortin I, and calpactin II, is an ~ 40 kDa protein with phospholipase A2 inhibitory activity. Since phospholipase A2 is required for the biosynthesis of the potent mediators of inflammation, prostaglandins and leukotrienes, Annexin A1 may have anti-inflammatory activity. Human Annexin A1 shares 88 and 89% identity with mouse and rat Annexin A1, respectively.