CX3C Chemokines and Receptors

The lone CX3C (delta) subfamily member, fractalkine, has three intervening aa between the first two cysteine residues. It is a transmembrane protein with a chemokine domain attached to a long mucin-like stalk. Membrane-bound fractalkine has been shown to promote adhesion of leukocytes. The soluble chemokine domain of human fractalkine is chemotactic for T cells and monocytes, while the soluble chemokine domain of mouse fractalkine chemoattracts neutrophils and T-lymphocytes, but not monocytes.