Description
Fractalkine, also known as CX3C motif chemokine 1, CX3CL1, neurotactin and small-inducible cytokine D1, is the only member of the CX3C subfamily of the chemokine superfamily (1). Mature human Fractalkine consists of an N-terminal chemokine domain with a CX3C motif and a mucin-like stalk region in the extracellular domain (ECD), a transmembrane segment and a short cytoplasmic domain (1, 2). The soluble form of Fractalkine is generated via ADAM10 and ADAM17 cleavage (1). Within the ECD, human Fractalkine shares 59% amino acid sequence identity with both mouse and rat Fractalkine. Fractalkine exists as both a membrane-bound adhesion molecule and as a soluble proinflammatory chemoattractant and anti-inflammatory neuroprotective agent (1-3). The expression of CX3CL1 is higher in spinal metastases from kidney cancer (4). The expression of CX3CL1 was also reported to be up-regulated in endothelial cells and microglia by inflammatory signals. Membrane-bound CX3CL1 has been shown to promote adhesion of leukocytes. The soluble chemokine domain of human CX3CL1 was reported to be chemotactic for T cells and monocytes while the soluble chemokine domain of mouse CX3CL1 was reported to chemoattract neutrophils and T-lymphocytes but not monocytes (5). Most of the functions of CX3CL1 are exerted through the CX#CL1/CX3CR1 axis which has the therapeutic prospect (5, 6). Our Avi-tag Biotinylated Recombinant Fractalkine features biotinylation at a single site contained within the Avi-tag, a unique 15 amino acid peptide. Protein orientation will be uniform when bound to streptavidin-coated surface due to the precise control of biotinylation and the rest of the protein is unchanged so there is no interference in the protein's bioactivity