– Fractalkine(CX3CL1) is a single-pass type I membrane protein and belongs to the intercrine delta family. It consists of an extracellular NH2-terminal domain, a mucin-like stalk, a transmembrane α helix, and a short cytoplasmic tail. CX3CL1 exists in two forms: as a membrane-anchored or as a shed 80-95K glycoprotein. Soluble CX3CL1 is generated by limited proteolysis on the cell surface, and a disintegrin and metallopeptidase 10 (ADAM10) and ADAM17/tumor necrosis factor-α-converting enzyme (ADAM17/TACE) participate in this shedding. It has been suggested that ADAM10 acts in the constitutive shedding, and ADAM17 acts in response to cell activation. The protein may play a role in regulating leukocyte adhesion and migration processes at the endothelium.