ICAM3 - Intercellular adhesion molecule 3 | Elisa - Clia - Antibody - Protein

Background:

Intercellular Adhesion Molecule 3 (ICAM-3) is another member of the ICAM family of proteins, although its functions and characteristics differ from ICAM-1 and ICAM-2 ICAM-3 is also a glycoprotein, but it has a different structure compared to ICAM-1 and ICAM-2. It contains five extracellular immunoglobulin-like domains, similar to ICAM-1, but its cytoplasmic tail is shorter. ICAM-3 is primarily involved in the activation and adhesion of leukocytes, particularly lymphocytes. It helps in the binding of these cells to antigen-presenting cells (APCs) during immune responses. ICAM-3 plays a role in the activation of lymphocytes and antigen presentation, where APCs present antigens to T cells, initiating an immune response. ICAM-3 is mainly expressed on antigen-presenting cells (APCs), such as dendritic cells, macrophages, and B cells. It is also found on activated T cells. Dysregulation of ICAM-3 expression or function has been associated with various immune-related diseases, including autoimmune disorders and infections.

Protein Structure:

ICAM-3 is a type I transmembrane glycoprotein composed of five extracellular immunoglobulin-like domains, a single transmembrane segment, and a short cytoplasmic tail. This structure is similar to other members of the ICAM family, allowing it to participate in cell-cell adhesion and signaling.

Classification and Subtypes:

ICAM-3 is part of the intercellular adhesion molecule (ICAM) family, which includes ICAM-1, ICAM-2, ICAM-4, and ICAM-5. These molecules are classified based on their roles in cell adhesion and their immunoglobulin-like domain structures.

Function and Biological Significance:

ICAM-3 is crucial for the immune response, particularly during the early interactions between T cells and antigen-presenting cells (APCs). It serves as a ligand for LFA-1 (lymphocyte function-associated antigen-1), an integrin expressed on leukocytes. The interaction between ICAM-3 and LFA-1 facilitates the stable adhesion of T cells to APCs, enhancing T cell activation and proliferation. ICAM-3 also contributes to the formation of the immunological synapse, a specialized junction between T cells and APCs that is essential for effective immune signaling.

Interactions:

ICAM-3 primarily interacts with the integrin LFA-1 (CD11a/CD18). This binding is critical for leukocyte adhesion and migration during the immune response. Additionally, ICAM-3 can interact with other integrins and molecules involved in cell signaling and cytoskeletal organization, further influencing immune cell behavior.

Clinical Issues:

Alterations in ICAM-3 expression or function can impact immune system performance and contribute to various diseases. For example:

• Immune Deficiencies: Reduced ICAM-3 expression can impair T cell activation and immune responses.
• Autoimmune Diseases: Dysregulation of ICAM-3-mediated adhesion and signaling can contribute to the pathogenesis of autoimmune diseases.
• Cancer: ICAM-3 may play a role in tumor-immune interactions, influencing tumor progression and metastasis.

Summary:

ICAM-3 is a vital adhesion molecule in the immune system, facilitating the early stages of T cell activation and interaction with antigen-presenting cells. Its interaction with LFA-1 is crucial for stable leukocyte adhesion and effective immune responses. Understanding ICAM-3's role in immune regulation provides insights into potential therapeutic targets for immunodeficiencies, autoimmune diseases, and cancer.