Recombinant Human CXCL9/MIG Protein

CXCL9, a member of the alpha subfamily of chemokines that lack the ELR domain, was initially identified as a lymphokine-activated gene in mouse macrophages. Human CXCL9 was subsequently cloned using mouse MIG cDNA as a probe. The CXCL9 gene is induced in macrophages and in primary glial cells of the central nervous system specifically in response to IFN-gamma. CXCL9 has been shown to be a chemoattractant for activated T‑lymphocytes and TIL but not for neutrophils or monocytes. The human CXCL9 cDNA encodes a 125 amino acid residue precursor protein with a 22 amino acid residue signal peptide that is cleaved to yield a 103 amino acid residue mature protein. CXCL9 has an extended carboxy‑terminus containing greater than 50% basic amino acid residues and is larger than most other chemokines. The carboxy‑terminal residues of CXCL9 are prone to proteolytic cleavage resulting in size heterogeneity of natural and recombinant CXCL9. CXCL9 with large carboxy‑terminal deletions have been shown to have diminished activity in the calcium flux assay. A chemokine receptor (CXCR3) specific for CXCL9 and IP-10 has been cloned and shown to be highly expressed in IL-2-activated T‑lymphocytes. The E. coli‑expressed CXCL9 preparations produced at R&D Systems have been shown to contain greater than 80% full length CXCL9.