CD49d

CD49d is an integrin subunit that forms part of the VLA-4 (Very Late Antigen-4) receptor. This receptor is involved in cell adhesion and cell surface signaling processes. CD49d is expressed on various immune cells, including T cells, B cells, and monocytes, and plays a crucial role in their migration and function.

Structure[edit | edit source]

CD49d is a type I transmembrane protein that pairs with the beta1 integrin subunit (CD29) to form the VLA-4 receptor. The CD49d subunit is approximately 150 kDa in size and contains a large extracellular domain, a single transmembrane region, and a short cytoplasmic tail.

Function[edit | edit source]

The primary function of CD49d is to mediate the adhesion of immune cells to the vascular endothelium, a process that is essential for their migration into inflamed tissues. This is achieved through the interaction of VLA-4 with its ligands, VCAM-1 (Vascular Cell Adhesion Molecule-1) and fibronectin.

In addition to its role in cell adhesion, CD49d also contributes to cell surface signaling processes. For example, it has been shown to enhance the activation of T cells and to promote the survival and proliferation of B cells.

Clinical significance[edit | edit source]

Abnormal expression or function of CD49d has been associated with various diseases, including autoimmune diseases, inflammatory diseases, and cancer. For instance, high levels of CD49d expression have been observed in chronic lymphocytic leukemia (CLL) cells, and this has been linked to a more aggressive disease course.