| Description | Prepared from plasma shown to be non reactive for HBsAg, anti-HCV, anti-HBc, and negative for anti-HIV 1 & 2 by FDA-required tests | Protein Purity≥85% by SDS PAGEExtinction CoeffA280 nm = 0.631 at 1.0 mg/ml for pure C1qMolecular Weight400,000 Da (18 chains)General DescriptionRat C1q is purified from pooled normal rat serum. C1q is part of the C1 complex, which is the first complement component in the classical pathway of Protein Purity≥85% by SDS PAGEExtinction CoeffA280 nm = 0.631 at 1.0 mg/ml for pure C1qMolecular Weight400,000 Da (18 chains)General DescriptionRat C1q is purified from pooled normal rat serum. C1q is part of the C1 complex, which is the first complement component in the classical pathway of complement. The C1 complex is a non-covalent assembly of three different proteins (C1q, C1r, and C1s) bound together in a calcium-dependent complex. C1q has six extended arms with domains at the end of each arm that bind to the Fc domains of immunoglobulins such as IgG or IgM. When antibodies bind toantigens, forming immune complexes, they cluster allowing two or more of the six C1q arms to bind to the Fc domains of antibodies. Rat IgG2 is very efficient when compared to IgG1 in activating complement (Medgyesi, G.A et., al., 1981). This is in contrast to the human system in which IgG1 activates complement but not IgG2 (Redpath, S. et. al., 1998). The binding of multiple arms of C1q to immune complexes causes the two C1r proteins in the complex (protease zymogens) to auto-activate. The activated C1r proteases cleave and activate the two C1s protease zymogens in the complex. The activated C1s cleaves complement component C4 releasing C4a and initiating covalent attachment of C4b to the activating surface. Activated C1s also cleaves C2 and the larger fragment of C2 binds to the surface-attached C4b forming C4b,C2a, the C3/C5 convertase of the classical pathway.Rat IgG1 cannot activate complement whereas rat IgG2 does.Physical Characteristics & StructureThe apparent molecular weight of rat C1q as determined by gel filtration has been reported to be 400,000 by Veerhuis, R. et al., (1985) and is calculated to be 420,000 based on its amino acid sequence. Rat C1q is a high molecular weight complex of 18 polypeptide chains. Each of the six arms of rat C1q contains three chains, an A chain (~30,000 daltons), a B chain (~28,000 daltons) and a C chain (~26,000 daltons) as determined by SDS/polyacrylamide gel electrophoresis (Wing, M.G. et al., (1993)).FunctionThe biological functions of C1q are described above in the General Description and Physical Characteristics sections.ApplicationsRat C1q can be used to coat ELISA plates to capture and quantitate immune complexes in samples from rat models used for studying immune complex related diseases and conditions.GeneticsNCBI Gene ID numbers for rat C1q are: C1q A chain (298566), C1q B chain (29687), and C1q C chain (362634). The genes for C1q chains A, B and C are all located on chromosome 5. The UniprotKB primary accession numbers for rat C1q are: C1q A chain (P31720), C1q B chain (P31721), and C1q C chain (P31722).Precautions/Toxicity/HazardsThis protein is purified from animal plasma/serum and therefore precautions appropriate for handling any animal blood-derived product must be used.ReferencesMedgyesi, G.A et., Miklos, K., Kulics, J., Fust, G., and Gergely, J. Bazin, H. (1981). Classes and subclasses of rat antibodies: reaction with the antigen and interaction of the complex with the complement system. Immunology 43, 171-176.Redpath, S., Michaelsen, T., Sandlie, I. and Clark, M. R. (1998). Activation of complement by human IgG1 and human IgG3 antibodies against the human leucocyte antigen CD52. Immunology 93, 595–600.Veerhuis, R., Van Es, L.A. and Daha, M.R. (1985). In vivo degradation of rat C1q induced by intravenous injection of soluble IgG aggregates. Immunology 54, 801-810.Wing, M.G., Seilly, D. J., Bridgman, D.J. and Harrison, R.A. (1993). Rapid isolation and biochemical characterization of rat C1 and C1q. Molecular Immunology 30, 433-440... Read More | C1q separated from C1r and C1s and from other stabilizing proteins tends to aggregate easily. Because it was isolated and studied in numerous research laboratories, many buffers have been used to stabilize concentrated C1q and prevent aggregation. About half of the scientists prefer high salt and C1q separated from C1r and C1s and from other stabilizing proteins tends to aggregate easily. Because it was isolated and studied in numerous research laboratories, many buffers have been used to stabilize concentrated C1q and prevent aggregation. About half of the scientists prefer high salt and the other prefer 40% glycerol in the storage buffer.C1q is purified from pooled normal human plasma. C1q is part of the C1 complex and this complex is the first complement component in the cascade referred to as the classical pathway of complement. C1 is actually a non-covalent assembly of three different proteins (C1q, C1r, and C1s) bound together in a calcium-dependent complex. C1q has six extended arms with domains at the end of each arm that bind to the Fc domains of immunoglobulins. When antibodies bind to antigens forming immune complexes they cluster allowing two or more of its six arms of C1q to bind to the Fc domains of antibodies such as IgG or IgM. The binding of multiple arms to immune complexes causes the two C1r proteins in the complex (protease zymogens) to auto-activate producing two C1r proteases that cleave and activate the two C1s protease zymogens in the complex. Activated C1s cleaves complement component C4 releasing C4a and initiating covalent attachment of C4b to the activating surface. Activated C1s also cleaves C2 and the larger fragment of C2 binds to the surface-attached C4b forming C4b,C2a which is the C3/C5 convertase of the classical pathway.Extinction Coeff.A₂₈₀ nm = 0.68 at 1.0 mg/ml for pure C1q Molecular weight:410,000 Da (18 chains)Preservative:None, 0.22 µm filtered.Source:Normal human serum (shown by certified tests to be negative for HBsAg, HTLV-I/II, STS, and for antibodies to HCV, HIV-1 and HIV-II).Physical Characteristics & StructureC1q is a high molecular weight complex of 18 polypeptide chains. Each of the six arms of C1q contains three chains, an A chain (26,000 daltons), a B chain (25,000 daltons) and a C chain (24,000 daltons). The three chains are coiled into a collagen-like triple helix over approximately half their length. Half of this collagen region forms a central core where all 18 chains come together. The chains are joined in this core by disulfides in the pattern A-B and C-C. There is a bend in the center of the collagen region allowing the arms to extend away from each other. Globular heads at the far ends of the collagen arms possess binding sites for Fc domains of immunoglobulins. C1 complex is composed of one C1q molecule (410,000 daltons), two C1r molecules (92,000 daltons) and two C1s molecules (86,000 daltons). The complex is stable in the presence of calcium, but easily dissociates if calcium is removed. When C1 is activated the C1r and C1s subunits are each cleaved into two chain molecules due to proteolytic activation. Thus, the SDS gel pattern of C1 is very complex. Function The biological functions of C1q are described above in the General Description and Physical Characteristics sections. C1q functional activity may be assayed using C1q-depleted serum and EA cells. These assays are extremely sensitive to C1q typically yielding 50% lysis with less than 2 ng C1q in assays measuring the lysis of EA cells. AssaysThe unit of classical pathway activity is the CH50. A similar unit, the C1qH50, is used to quantitate the activity of C1q. A C1qH50 unit is the amount of functional C1q needed to lyse 50% of 3×10^7 EA cells (antibody-sensitized sheep erythrocytes) when that amount of C1q is incubated with 5-20 µL of C1q-Dpl in GVB++ in a total volume of 500 µL for 30 min at 37℃. This amount of C1q indicates the sensitivity of the assay for C1q which is typically about 1 ng C1q with 10 µL C1q-Dpl. See the Certificate of Analysis for lot specific values.ApplicationsC1q is used to coat ELISA plates to capture and quantitate immune complexes in clinical samples. A number of commercial companies sell diagnostic kits for immune complex detection and quantitation. These kits are based on the ability of C1q to bind well to immune complexes, but to not bind significantly to monomeric immunoglobulins. GeneticsThe EMBL/Genbank cDNA accession numbers are: C1q A chain (P02745), C1q B chain (P02746), and C1q C chain (P02747). The genes for C1q chains A, B and C are all located on chromosome 1p in the order A-C-B. DeficienciesDeficiencies of each of the three components of C1 have been found. Patients lacking C1q generally have immune-complex-mediated renal disease and skin lesions. Like all patients lacking early classical pathway components C1q deficient individuals are prone to systemic lupus erythrematosis (SLE) and recurrent pyogenic infections. They lack classical pathway function and may or may not exhibit C1q antigen in blood.DiseasesSee section titled Deficiencies above. Precautions/Toxicity/HazardsThis protein is purified from human serum and therefore precautions appropriate for handling any blood-derived product must be used even though the source was shown by certified tests to be negative for HBsAg, HTLV-I/II, STS, and for antibodies to HCV, HIV-1 and HIV-II... Read More | Purity:>95%, by SDS-PAGE visualized with Coomassie® Blue Staining.Description：CD200 R1, also known as OX-2 receptor, is a 90 kDa transmembrane protein in the immunoglobulin superfamily and is important in the regulation of myeloid cell activity. The human CD200 R1 cDNA encodes a 325 Purity:>95%, by SDS-PAGE visualized with Coomassie® Blue Staining.Description：CD200 R1, also known as OX-2 receptor, is a 90 kDa transmembrane protein in the immunoglobulin superfamily and is important in the regulation of myeloid cell activity. The human CD200 R1 cDNA encodes a 325 amino acid (aa) precursor that includes a 28 aa signal sequence, a 215 aa extracellular domain (ECD), a 21 aa transmembrane segment, and a 61 aa cytoplasmic domain. The ECD is composed of one Ig-like V-type domain and one Ig-like C2-type domain. Within the ECD, human CD200 R1 shares 56% aa sequence identity with both mouse and rat CD200 R1. Alternate splicing of the human CD200 R1 mRNA generates four isoforms, two of which are truncated in the Ig-C2 domain and are likely secreted. In human, a separate CD200 RL gene encodes a protein that shares 81% ECD aa identity with CD200 R1. In mouse, at least four genes for CD200 R1-like molecules have been described. CD200 R1 expression is restricted primarily to mast cells, basophils, macrophages, and dendritic cells, while its ligand, CD200, is widely distributed. Disruption of this receptor-ligand system by knockout of the CD200 gene in mice leads to increased macrophage number and activation and predisposition to autoimmune disorders. Association of CD200 with CD200 R1 takes place between their respective N-terminal Ig-like domains. The capacity of CD200 R1-like molecules to interact with CD200 is controversial. CD200 R1 propagates inhibitory signals despite lacking a cytoplasmic ITIM (immunoreceptor tyrosine-based inhibitory motif). CD200 R1-like molecules, in contrast, are potentially activating receptors by means of their association with DAP12. CD200R1 signaling inhibits the expression of proinflammatory molecules including TNFs, IFNs, and inducible nitric oxide synthase in response to selected stimuli, which implicate that CD200/CD200R1 inhibitory signaling pathway plays a prominent role in limiting inflammation in a wide range of inflammatory diseases. Furthermore, the CD200/CD200R inhibitory signaling constitutes one of the most suitable endogenous immunoregulatory molecule candidate to restore the immune suppressive status of the CNS altered in chronic neuroinflammatory situations... Read More | Purity>97% by SDS-PAGE and HPLC analyses.FunctionMay be involved in macrophage-mediated cellular proliferation. It is mitogenic for fibroblasts and smooth muscle but not endothelial cells. It is able to bind EGF receptors with higher affinity than EGF itself and is a far more potent mitogen for Purity>97% by SDS-PAGE and HPLC analyses.FunctionMay be involved in macrophage-mediated cellular proliferation. It is mitogenic for fibroblasts and smooth muscle but not endothelial cells. It is able to bind EGF receptors with higher affinity than EGF itself and is a far more potent mitogen for smooth muscle cells than EGF. Also acts as a diphtheria toxin receptor.Background:Human HB-EGF (Heparin-Binding EGF-like growth factor) is a 12-16 kDa member of the EGF family of peptide growth factors (1-3). Also known as the DTR (diphtheria toxin receptor), it is further classified as a group 2 ErbB ligand based on its ability to activate both the EGF/ErbB1 and ErbB4 receptors (4, 5). HB-EGF is synthesized as a 208 amino acid (aa) type I transmembrane preproprecursor (1, 6). It contains a 19 aa signal sequence, a 43 aa prosegment, an 86 aa mature region (aa 63-148), an 11 aa juxtamembrane cleavage peptide, a 24 aa transmembrane segment, and a 25 aa cytoplasmic tail (aa 184-208). As an integral membrane protein, HB-EGF is expressed as a 19-27 kDa protein in mammalian cells (7-9). The variability in molecular weight (MW) is attributed to heterogeneity in glycosylation and/or the utilization of multiple proteolytic cleavage sites during maturation. Mature HB-EGF is a soluble peptide that arises from proteolytic processing of the transmembrane form. It possesses an EGF-like domain between aa 104-144, and a heparin-binding motif between aa 93‑113. Although the aa range for "mature" HB-EGF is typically stated to be Asp63-Leu148, potential N-terminal start (cleavage) sites also exist at Gly32, Arg73, Val74, Ser77 and Ala82 (8, 10-12). Thus, differential processing (in part) likely accounts for the 16-23 kDa range in MW noted for mammalian-derived mature HB-EGF. Proteases suggested to contribute to HB-EGF processing include TACE, MMP-3 and -7, ADAM-17 and ADAM-12 (11, 13-16). When expressed recombinantly in E.coli, HB-EGF (aa 73-148) runs at 14 kDa in SDS-PAGE; when expressed in Baculovirus, HB-EGF (aa 63-148, 77-148 and 32-148) runs at 18 kDa, 15 kDa, and 19 kDa respectively (8, 12, 17). Over aa 63-148, human HB-EGF- shares 76% and 73% aa sequence identity with rat and mouse HB-EGF, respectively (1, 18). Cells known to express HB-EGF include bronchial epithelium (19), visceral and vascular smooth muscle (20, 21), CD4+ T cells (22), cardiac muscle (23), glomerular podocytes (24), keratinocytes (13) and IL-10-secreting regulatory macrophages (25). As noted earlier, HB-EGF is known to bind to both 170 kDa EGFR and 180 kDa ErbB4, and through heterodimerization, ErbB2 (13, 26). Activity associated with ErbB4 binding appears to be limited to non-mitogenic actions, while EGFR binding induces both mitogenic and non-mitogenic activity... Read More |