| Description | Inquire | 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 | TEV Protease is the 241 amino acid (aa), 27 kDa catalytic domain of the nuclear inclusion a (NIa) protein encoded by the potyvirus, tobacco etch virus (TEV). It may be used in biotechnology to cleave affinity tags from recombinant proteins, either co-translationally orin vitrofollowing purification.TEV Protease is the 241 amino acid (aa), 27 kDa catalytic domain of the nuclear inclusion a (NIa) protein encoded by the potyvirus, tobacco etch virus (TEV). It may be used in biotechnology to cleave affinity tags from recombinant proteins, either co-translationally orin vitrofollowing purification. Its high specificity and activity at a wide range of pH and ionic strength make TEV Protease more versatile than many other proteases used for the same purpose. Unlike factor Xa, enteropeptidase or thrombin, TEV Protease has not been found to cleave at unintended sites, even when present at a high concentration. TEV Protease is a 3C-type protease that cleaves substrates with a consensus sequence of ENLYFQG. Cleavage occurs between Q and G. Since the final aa remains on the cleaved protein where it could potentially affect structure or function, substitution of a variety of aa have been tested. In order of efficiency, S, A, M, Y, D, N, E, K or L may be effectively used in place of G. Several of the remaining aa may also vary, giving a final consensus sequence of ExxYF(M)Q(E)/G(S, A or others) where aa in parenthesis are alternatives and x is any aa. The autocatalytic site of NIa at S2256 has been mutated to an N for improved stability of the protease.Tobacco Etch Virus Protease is a highly site-specific cysteine protease that is found in the tags from fusion proteins. The optimal temperature for cleavage is 30°C. It is recommended that the cleavage for each fusion protein be optimized by varying the amount of recombinant viral TEV protease, reaction time, or incubation temperature. It can be removed by Ni2+ affinity resin... Read More | Purity:>90%, by SDS-PAGE visualized with Coomassie® Blue Staining.Description：IL12 is a cytokine that acts on T and natural killer cells, and has a broad array of biological activities. It is a disulfide-linked heterodimer composed of the 40 kD cytokine receptor like subunit and a 35 Purity:>90%, by SDS-PAGE visualized with Coomassie® Blue Staining.Description：IL12 is a cytokine that acts on T and natural killer cells, and has a broad array of biological activities. It is a disulfide-linked heterodimer composed of the 40 kD cytokine receptor like subunit and a 35 kD subunit. This cytokine is expressed by activated macrophages that serve as an essential inducer of Th1 cells development. IL12 has been found to be important for sustaining a sufficient number of memory/effector Th1 cells to mediate long-term protection to an intracellular pathogen. Recombinant human IL12 protein, fused to His-tag at C-terminus, was expressed in insect cells using baculovirus expression system and purified by using conventional chromatography techniques... Read More | Purity:>95%, by SDS-PAGE visualized with Coomassie® Blue StainingDescription:ROR1 (Receptor tyrosine kinase-like orphan receptor 1), also known as neurotrophic tyrosine kinase receptor-related 1 (NTRKR1), is a member of the ROR family within the receptor tyrosine kinases (RTK) superfamily. Purity:>95%, by SDS-PAGE visualized with Coomassie® Blue StainingDescription:ROR1 (Receptor tyrosine kinase-like orphan receptor 1), also known as neurotrophic tyrosine kinase receptor-related 1 (NTRKR1), is a member of the ROR family within the receptor tyrosine kinases (RTK) superfamily. Two ROR family members (ROR1 and ROR2) have been identified and are characterized by their intracellular tyrosine kinase domains, which are highly related to those of the Trk-family receptor tyrosine kinases, and by their extracellular Frizzled-like cysteine-rich domains and kringle domains, common to receptors of the Wnt family members. Human ROR1 is a type I transmembrane protein with 937 amino acids in length. It contains a 29 amino acid signal sequence, a 377 amino acid extracellular domain (ECD), a 21 amino acid transmembrane segment, and a 510 amino acid cytoplasmic region. Human ROR1 shares 97% and 58% amino acid sequence identity with mouse ROR1 and human ROR2, respectively. ROR1 has been shown to play crucial roles in developmental morphogenesis by acting as receptors or co-receptors to mediate Wnt5a-induced signaling. The bioactivity of ROR1 is measured by its ability to bind biotinylated recombinant mouse Wnt-5a in a functional ELISA... Read More |