ChemiSCREEN C3aR Membrane Preparation

C3a, along with C4a and C5a, is a 77 amino acid anaphylotoxin generated by proteolytic cleavage during activation of the complement pathway (Ember, 1997). The anaphylotoxins strongly promote inflammation by recruiting leukocytes, particularly basophils, eosinophils, neutrophils and monocyte (Martin, 1997). The proinflammatory properties of C3a are mediated by interaction between the peptide and a 7-TM G-protein coupled receptor, C3aR (Crass, 1996). Genetic and pharmacological inhibition of C3a/C3aR interaction indicates an important role for C3aR in allergic asthsma Humbles, 2000; Drouin, 2002). C3a/C3aR also enhances the effect of SDF-1 in promoting retention of haematopoietic stem/progenitor cells within the bone marrow (Rataiczak, 2004). Chemicon′s C3aR membrane preps are an ideal tool for screening for compounds that disrupt binding of C3a to C3aR. The membranes have been shown to bind to 125I-labeled C3a with a Kd of 0.06 nM.

Full-length human C3aR cDNA

Human C3aR GPCR membrane preparation for Radioligand binding Assays.

Radioligand binding assay

GPCR Class: A

Protein Target: C3aR

Target Sub-Family: Anaphylotoxin

Membranes were adjusted to 0.5mg protein/mL in 50 mM Tris-HCL, pH 7.4, 10% glycerol and 1% BSA, rapidly frozen, and stored at -80°C. One vial contains 500 units, where a unit is the amount of membrane that will yield greater than 1000 cpm specific binding of ¹²⁵I-labeled C3a (0.04 nM input concentration).

Maintain frozen at -70°C for up to 2 years. Do not freeze and thaw.

Bmax for [¹²⁵I]C3a binding: 1.9 pmol/mg protein
Kd for [¹²⁵I] C3a binding: ~ 0.06 nM

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