The chemokine SDF-1a and its GPCR receptor CXCR4 have a one-to-one specificity that is unique among chemokines and their receptors. SDF-1a binds to CXCR4 expressed on hematopoietic and lymphopoietic cells, and directs their trafficking to and retention in hemato-and lymphatopoietic organs and sites of inflammation (Kucia et al., 2004). CXCR4 is expressed on several tumor cell lineages, and might be responsible for metastasis to sites of SDF-1a expression, such as bone and lymph nodes (Muller et al., 2001). In addition, CXCR4 is a coreceptor for the HIV envelope glycoprotein gp120 (Feng et al., 1996). Small molecule antagonists of CXCR4 have been developed and shown to inhibit infectivity of T-tropic HIV strains and to impair growth of brain tumors (Arakaki et al., 1999; Rubin et al., 2003). Chemicon's CXCR4 membrane preparations are crude membrane preparations made from our proprietary stable recombinant cell lines to ensure high-level of GPCR surface expression; thus, they are ideal tools for screening for antagonists of interactions between CXCR4 and SDF-1a. Radiolabeled SDF-1a binds to the CXCR4 membranes with a Kd of 0.9 nM. With 0.04-0.13 nM 125I-labeled SDF-1a, an approximately 3-fold window of specific binding is obtained.
Application: Radioligand binding assay and GTPgammaS binding.
Biochem Physiol Actions: Protein Target: CXCR4
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