Recombinant Human Fc gamma RIIA / CD32a (R167) Protein, 1mg

Background
Receptors for the Fc region of IgG (Fc γ R) are members of the Ig superfamily that function in the activation or inhibition of immune responses. Three classes of human Fc γ Rs: RI (CD64), RII (CD32), and RIII (CD16), which generate multiple isoforms, are recognized. There are three genes for human Fcγ RII /CD32 (A, B, and C) and one for mouse Fcγ RII B (CD32B). CD32 is a low affinity receptor for IgG. The activating isoform, CD32A, is expressed on monocytes, neutrophils, platelets and dendritic cells. CD32A is expressed on many immune cell types (macrophage, neutrophil, eosinophils, platelets, dendritic cells and Langerhan cells), where inhibitory ITIM­bearing receptors may also be coexpressed and co­engaged by specific ligands. CD32A delivers an activating signal upon ligand binding, and results in the initiation of inflammatory responses including cytolysis, phagocytosis, degranulation and cytokine production. The responses can be modulated by signals from the coexpressed inhibitory receptors such as CD32B, and the strength of the signal is dependent on the ratio of expression of the activating and inhibitory receptors.

Source
Recombinant Human CD32a (R167), His Tag (SPR & BLI verified) (CDA-H5221) is expressed from human 293 cells (HEK293). It contains AA Ala 36 - Ile 218 (Accession # P12318-1).
Predicted N-terminus: Ala 36

Molecular Characterization
This protein carries a polyhistidine tag at the C-terminus.
The protein has a calculated MW of 21.6 kDa. The protein migrates as 25-35 kDa under reducing (R) condition (SDS-PAGE) due to glycosylation.

Endotoxin
Less than 1.0 EU per μg by the LAL method.
 
Purity
>95% as determined by SDS-PAGE.

Formulation
Lyophilized from 0.22 μm filtered solution in PBS, pH7.4. Normally trehalose is added as protectant before lyophilization.

Reconstitution
Please see Certificate of Analysis for specific instructions.
For best performance, we strongly recommend you to follow the reconstitution protocol provided in the CoA.

Storage
For long term storage, the product should be stored at lyophilized state at -20°C or lower.
Please avoid repeated freeze-thaw cycles.
No activity loss is observed after storage at:
4-8°C for 12 months in lyophilized state;
-70°C for 3 months under sterile conditions after reconstitution.

Bioactivity
Immobilized Human CD32a (R167), His Tag (SPR & BLI verified) (Cat. No. CDA-H5221) on CM5 Chip via anti-His antibody, can bind  Rituximab with an affinity constant of 3.12 μM as determined in a SPR assay (Biacore T200) (Routinely tested).

Loaded Rituximab on Protein A Biosensor, can bind Human CD32a (R167), His Tag (SPR & BLI verified) (Cat. No. CDA-H5221) with an affinity constant of 1.5 μM as determined in BLI assay (ForteBio Octet Red96e) (QC tested).

Loaded Human CD32a (R167), His Tag (SPR & BLI verified) (Cat. No. CDA-H5221) on HIS1K Biosensor, can bind Rituximab with an affinity constant of 1.4 μM as determined in BLI assay (ForteBio Octet Red96e) (Routinely tested).

References

(1) Ravetch JV. et al., 2001, Annu Rev Immunol. 19: 275-83.
(2) Takai T. 2002, Nature Rev Immunol. 2: 580-92.
(3) Nagarajan S. et al., 2000, Blood. 3: 1069-77.(3) Güssow D., et al., 1987, J. Immunol. 139 (9): 3132–8.
(4) Gorevic P.D., et al., 1986, Proc. Natl. Acad. Sci. U.S.A. 83:7908-7912.