Capillary Morphogenesis Gene-2 (CMG-2) is a widely expressed anthrax toxin receptor (ATR) family protein (1-4). CMG-2 is a ~55 kD protein that contains a 31 amino acid (aa) signal sequence, a 287 aa extracellular domain (ECD), a 21 aa transmembrane sequence, and a 148 aa cytoplasmic domain. Unlike human CMG-2 which has four isoforms, only one sequence has been reported for mouse CMG-2. The main functional domain of CMG-2 is an extracellular integrin-like von Willebrand factor type A (VWA) domain with a metal ion dependent adhesion site (MIDAS), through which it adheres selectively to collagen type IV and laminin (1-6). CMG-2 isoform 2 is induced in HUVEC as they undergo capillary formation in collagen matrices in vitro (4). In humans, CMG-2 is mutated in juvenile hyaline fibromatosis and infantile systemic hyalinosis disorders, and several of these mutations result in loss of laminin binding (7). CMG-2 and the related protein ATR/TEM8 serve as receptors for the protective antigen (PA) of Bacillus anthracis (1, 2). After binding the VWA domain, PA undergoes furin-type cleavage, forms a heptameric receptor/PA pre-pore and binds LF or EF toxin subunits (6, 8, 9). Transport to low pH endosomes, which requires CMG-2 ubiquitination and interaction with the LDL receptor related protein LRP6 (10, 11), allows PA pore formation and release of toxin to the cytoplasm (11, 12). Soluble CMG-2 VWA domain acts as a dummy receptor that can protect cultured cells from anthrax intoxication (2). Within the extracellular region, mouse CMG-2 shares 84%, 91%, 80%, and 83% amino acid sequence homology with human, rat, cow, and dog CMG-2, respectively. CMG-2 VWA domain also shares 60% aa identity with ATR/TEM8.
Source:Human CD33 signal peptide (Met 1-Ala 16) Mouse CMG-2 (Gly 26-Gly 318) HHHHHH. A DNA sequence encoding the extracellular domain of mouse CMG-2 (Gly 26-Gly 318; Accession # Q6DFX2) (Strausberg, R.L. et al., 2002, Proc. Natl. Acad. Sci. USA 99(26):16899) was fused to the signal peptide of human CD33 at the N-terminus and to a 6X histidine tag at the C-terminus. The protein was expressed in a mouse myeloma cell line, NS0.
Molecular Mass:The mature recombinant mouse CMG-2 contains 299 amino acid residues with a calculated molecular mass of approximately 32 kD. As a result of glycosylation, the recombinant protein migrates as an approximately 32-35 kD protein in SDS-PAGE under reducing conditions.
Endotoxin Level:< 1.0 EU per 1 μg of the protein as determined by the LAL method.
Activity:Measured by its ability to bind anthrax protective antigen (PA) in a functional ELISA (Scobie H.M. et al., 2003, Proc. Natl. Acad. Sci. USA 100:5170). Immobilized PA at 1.5ug/ml (100 μL/well) can bind rmCMG-2 with a linear range of 0.08-5.0ug/ml in a functional ELISA assay.
Storage and Stability:Samples are stable for up to twelve months from date of receipt at -20°C. Upon thawing, this protein, in the presence of a carrier protein, can be stored under sterile conditions at 2-8°C for one month or at -20°C in a manual defrost freezer for three months without detectable loss of activity. Avoid repeated freeze-thaw cycles.
