Hu Recom Fractalkine (CX3CL1), 25 µg

A chemokine of the CX3C family, this recombinant human Fractalkine (CX3CL1) is supplied by STEMCELL Technologies as a lyophilized powder expressed in CHO cells. The protein is characterized by a C-X3-C cysteine motif within its chemokine domain, followed by an extended mucin-like stalk, a transmembrane region, and a C-terminal intracellular domain. The protein signals through a single receptor, CX3CR1, expressed on monocytes, natural killer cells, T cells, microglia, and smooth muscle cells.

Fractalkine is upregulated in endothelial cells by inflammatory signals and is synthesized as a membrane-bound molecule that mediates cell migration and adhesion. Cleavage at the base of the stalk by metalloproteinases generates a soluble chemokine that acts as a potent chemoattractant of target cells. The protein has been implicated in the pathology of inflammatory diseases such as atherosclerosis and other vascular diseases, and also exhibits anti-apoptotic functions.

The lyophilized product is dialyzed against phosphate-buffered saline and has a predicted molecular mass of 50 - 75 kDa. Specific activity is ≥ 666 units/mg, determined by Ca2+ mobilization assay in CHO-K1/Gα15/hCX3CR1 cells, with a stated EC50 of ≤ 1.5 μg/mL and an example EC50 of 0.47 ng/mL. Purity is ≥ 95%, and the endotoxin level is ≤ 0.2 EU/μg protein as measured by kinetic Limulus amebocyte lysate (LAL) analysis. Cross-reactivity is reported for human and mouse. The vial should be centrifuged before opening, and the product reconstituted in sterile water or PBS to at least 0.1 mg/mL by pipetting the solution down the sides of the vial without vortexing. Store at -80°C; the product is stable as supplied for 12 months from the date of receipt. After reconstitution, store at 2 - 8°C for up to 1 week or at -20°C to -80°C for up to 3 months, avoiding repeated freeze-thaw cycles.