补体系统 (Complement System)

C1q associates with the proenzymes C1r and C1s to yield C1, the first component of the serum complement system. The collagen-like regions of C1q interact with the Ca(2+)-dependent C1r(2)C1s(2) proenzyme complex, and efficient activation of C1 takes place on interaction of the globular heads of C1q with the Fc regions of IgG or IgM antibody present in immune complexes.

Complement C5 Protein, Human, Recombinant (Complement C5a) is expressed in E. coli expression system. The predicted molecular weight is 8.3 kDa and the accession number is P01031.

Complement C3a Protein, Human, Recombinant is expressed in E. coli expression system. The predicted molecular weight is 13 KDa and the accession number is P01024.

Complement C3a Protein, Mouse, Recombinant is expressed in E. coli expression system. The predicted molecular weight is 9 KDa and the accession number is P01027.

Mannose-Binding Protein C (MBP-C) belongs to the Collectin family of innate immune defense proteins. MBL binds to an array of carbohydrate patterns on pathogen surfaces. Collectin family members share common structural features: a cysteine rich amino-terminal domain, a collagen-like region, an α-helical coiled-coil neck domain and a carboxy terminal C-type Lectin or carbohydrate recognition domain (CRD). MBL homotrimerizes to form a structural unit joined by N-terminal disulfide bridges. These homotrimers further associates into oligomeric structures of up to 6 units. Whereas two forms of MBL proteins exist in rodents and other animals. Human MBL-2 is 25 kDa. Human MBL-2 is a secreted glycoprotein that is synthesized as a 248 amino acid (aa) precursor that contains a 20 aa signal sequence, a 21 aa cysteine-rich region, a 58 aa collagen-like segment and a 111 aa C-type lectin domain that binds to neutral bacterial carbohydrates.

Complement C3 Protein, Human, Recombinant (His) is expressed in HEK293 mammalian cells with His tag. The predicted molecular weight is 186.43 kDa and the accession number is P01024.

Complement C5a Protein, Mouse, Recombinant is expressed in E. coli expression system. The predicted molecular weight is 9 kDa and the accession number is P06684.

C8 is a constituent of the membrane attack complex. C8 binds to the C5B-7 complex, forming the C5B-8 complex. C5-B8 binds C9 and acts as a catalyst in the polymerization of C9. The gamma subunit seems to be able to bind retinol. Complement C8g Protein, Human, Recombinant (His) is expressed in E. coli expression system with N-6xHis tag. The predicted molecular weight is 26.4 kDa and the accession number is P07360.

C1QA Protein, Human, Recombinant (GST) is expressed in E. coli expression system with GST tag. The predicted molecular weight is 50.58 kDa and the accession number is P02745.

MASP2 Protein, Mouse, Recombinant (His) is expressed in E. coli expression system with C-His tag. The predicted molecular weight is 46.6 kDa and the accession number is Q91WP0.

Complement factor D is a serine protease essential for the activation of the alternative pathway and is expressed in the kidney, adipocytes, and macrophages. Factor D is found at relatively high levels in glomeruli suggesting that this component of the complement cascade could influence renal pathophysiology.Complement factor D or alternative pathway activation is needed to prevent spontaneous accumulation of C3 and IgM deposits within the mesangium. Complement Factor D CFD Protein, Rhesus macaque, Recombinant (His) is expressed in HEK293 mammalian cells with C-His tag. The predicted molecular weight is 25.7 kDa and the accession number is H9EXC1-1.

Receptor for the chemotactic and inflammatory peptide anaphylatoxin C5a. The ligand interacts with at least two sites on the receptor: a high-affinity site on the extracellular N-terminus, and a second site in the transmembrane region which activates downstream signaling events. Receptor activation stimulates chemotaxis, granule enzyme release, intracellular calcium release and superoxide anion production. C5AR1 Protein-VLP, Human, Recombinant (His) is expressed in HEK293 mammalian cells with C-10xHis tag. The predicted molecular weight is 41.1 kDa and the accession number is P21730.

Receptor for the chemotactic and inflammatory peptide anaphylatoxin C5a. The ligand interacts with at least two sites on the receptor: a high-affinity site on the extracellular N-terminus, and a second site in the transmembrane region which activates downstream signaling events. Receptor activation stimulates chemotaxis, granule enzyme release, intracellular calcium release and superoxide anion production. C5AR1 Protein, Human, Recombinant (Cell-Free, His) is expressed in E. coli expression system with C-10xHis tag. The predicted molecular weight is 40.7 kDa and the accession number is P21730.

Factor D cleaves factor B when the latter is complexed with factor C3b, activating the C3bbb complex, which then becomes the C3 convertase of the alternate pathway. Its function is homologous to that of C1s in the classical pathway.

C1r B chain is a serine protease that combines with C1q and C1s to form C1, the first component of the classical pathway of the complement system.

May regulate the number of excitatory synapses that are formed on hippocampus neurons. Has no effect on inhibitory synapses. Plays a role in glucose homeostasis. Via AMPK signaling pathway, stimulates glucose uptake in adipocytes, myotubes and hepatocytes and enhances insulin-stimulated glucose uptake. In a hepatoma cell line, reduces the expression of gluconeogenic enzymes G6PC1 and PCK1 and hence decreases de novo glucose production.

Complement C3 Protein, Cynomolgus, Recombinant (His) is expressed in HEK293 mammalian cells with His tag. The predicted molecular weight is 186.40 kDa and the accession number is XP_005587776.1.

C1s B chain is a serine protease that combines with C1q and C1r to form C1, the first component of the classical pathway of the complement system. C1r activates C1s so that it can, in turn, activate C2 and C4.

Complement C6 Protein, Human, Recombinant (His) is expressed in HEK293 mammalian cells with His tag. The predicted molecular weight is 104 kDa and the accession number is AAA59668.1.

Complement C5 Protein, Cynomolgus, Recombinant (His) is expressed in HEK293 mammalian cells with His tag. The predicted molecular weight is 188.1 kDa and the accession number is XP_005580972.1.

C1QTNF1 is a secreted protein，contains 1 C1q domain and 1 collagen-like domain. C1qTNF proteins constitute a highly conserved family of Acrp30 Adiponectin paralogs that share a modular organization comprising an N-terminal signal peptide, a short variable region, a collagenous domain and a C-terminal globular domain. C1qTNF proteins are predicted to have trimeric structures that assemble into hexameric and higher order molecular forms. C1QTNF1 is a novel adipokine, providing a significant framework to further address the physiological functions and mechanisms of the action of this family of secreted glycoproteins in normal and disease states. C1QTNF1 increases the production of aldosterone. C1QTNF1 is vastly expressed in obese subjects as well as up-regulated in hypertensive patients, C1QTNF1 is identified molecular link between obesity and hypertension. C1QTNF1 expression may be associated with a low-grade chronic inflammation status in adipose tissues.

Complement is an integral component of the adaptive and innate immune systems and represents one of the major effector systems for the immune responses. The classical complement pathway is triggered by C1, a complex composed of the binding protein C1q and two proenzymes, C1r and C1s. Upon binding of IgG to the head of C1q, C1r undergoes autoactivation and in turn cleaves and activates C1s. C1r and C1s, the proteases responsible for activation and proteolytic activity of the C1 complex of complement, share similar overall structural organizations featuring five nonenzymic protein modules (two CUB modules surrounding a single EGF module, and a pair of CCP modules) followed by a serine protease domain. Besides highly specific proteolytic activities, both proteases exhibit interaction properties associated with their N-terminal regions. In contrast, C1r and C1s widely differ from each other by their glycosylation patterns: both proteins contain Asn-linked carbohydrates, but four glycosylation sites are present on C1r, and only two on C1s. As a highly specific serine protease, C1s executes the catalytic function of the C1 complex: the cleavage of C4 and C2, and thus instigates a sequence of activation steps of other components of the complement system, culminating in the formation of the membrane attack complex which induces cell lysis. Like other complement serine proteases C1s has restricted substrate specificity and it is engaged into specific interactions with other subcomponents of the complement system. The only other protein known to interact with C1s physiologically is SerpinC1, an inhibitor of serine protease, which inhibits C1s activity and thus plays a regulatory role in controlling the function of C1s enzyme.

Complement factor D is a serine protease essential for the activation of the alternative pathway and is expressed in the kidney, adipocytes, and macrophages. Factor D is found at relatively high levels in glomeruli suggesting that this component of the complement cascade could influence renal pathophysiology.Complement factor D or alternative pathway activation is needed to prevent spontaneous accumulation of C3 and IgM deposits within the mesangium. Complement Factor D CFD Protein, Mouse, Recombinant (hFc) is expressed in HEK293 mammalian cells with C-hFc tag. The predicted molecular weight is 52.2 kDa and the accession number is P03953-1.

MASP2 Protein, Cynomolgus, Recombinant (His) is expressed in E. coli expression system with C-His tag. The predicted molecular weight is 46.8 kDa and the accession number is A0A2K5UJY0.

Constituent of the membrane attack complex (MAC) that plays a key role in the innate and adaptive immune response by forming pores in the plasma membrane of target cells. Complement C8b Protein, Human, Recombinant (His) is expressed in E. coli expression system with N-6xHis tag. The predicted molecular weight is 67.0 kDa and the accession number is P07358.

Complement C8a Protein, Human, Recombinant (His) is expressed in E. coli.

Complement C4-B Protein, Human, Recombinant (His & SUMO) is expressed in E. coli.

C1s-A subcomponent Protein, Mouse, Recombinant (His) is expressed in HEK293 mammalian cells with His tag. The predicted molecular weight is 76.6 kDa and the accession number is AAH18319.1.

Complement C2 Protein, Human, Recombinant (His) is expressed in HEK293 mammalian cells with His tag. The predicted molecular weight is 82.5 kDa and the accession number is P06681-1.

Complement C3 Protein, Mouse, Recombinant (His & SUMO) is expressed in E. coli expression system with N-6xHis-SUMO tag. The predicted molecular weight is 55.3 kDa and the accession number is P01027.

Factor B which is part of the alternate pathway of the complement system is cleaved by factor D into 2 fragments: Ba and Bb. Bb, a serine protease, then combines with complement factor 3b to generate the C3 or C5 convertase.

Derived from proteolytic degradation of complement C5, C5a anaphylatoxin is a mediator of local inflammatory process. Binding to the receptor C5AR1 induces a variety of responses including intracellular calcium release, contraction of smooth muscle, increased vascular permeability, and histamine release from mast cells and basophilic leukocytes. C5a is also a potent chemokine which stimulates the locomotion of polymorphonuclear leukocytes and directs their migration toward sites of inflammation. Complement C5a Protein, Pig, Recombinant (His) is expressed in yeast with N-6xHis tag. The predicted molecular weight is 10.6 kDa and the accession number is P01032.

Complement C5a Protein, Mouse, Recombinant, Biotinylated is expressed in E. coli expression system. The predicted molecular weight is 9 kDa and the accession number is P06684.

C1QBP Protein, Human, Recombinant (His) is expressed in E. coli expression system with His tag. The predicted molecular weight is 24.8 kDa and the accession number is Q07021.

Complement C7 Protein, Human, Recombinant (hFc) is expressed in HEK293 mammalian cells with hFc tag. The predicted molecular weight is 118 kDa and the accession number is P10643.

CFI Protein, Mouse, Recombinant (His) is expressed in HEK293 mammalian cells with His tag. The predicted molecular weight is 66.75 kDa and the accession number is Q61129.

Complement C2 Protein, Human, Recombinant (hFc) is expressed in HEK293 mammalian cells with hFc tag. The predicted molecular weight is 110 kDa and the accession number is P06681-1.

Mannose-binding Lectin (MBL) is an acute phase protein bearing to the family of collectins produced by the liver as a monomer that forms a triple helix. Once released in serum, it further polymerizes forming dimers to octamers. The degree of serum polymerization is critical for the biological activity of MBL. MBL has higher affinity to microbial polysaccharides or their glycoconjugates. MBL was shown earlier to bind cell surfaces of bacteria, fungi, protozoa and viruses and acts as an acute-phase plasma protein (APP) during infection and inflammation. MBL activates the lectin-complement pathway, promotes opsonophagocytosis and modulates inflammation.

Complement factor I (CFI) is a serine protease which plays a key role in the modulation of complement system and the induced-fit factor responsible for controlling the complement-mediated processes. Complement factor I Protein, Mouse, Recombinant (His) is expressed in HEK293 mammalian cells with C-His tag. The predicted molecular weight is 66.39 kDa and the accession number is Q61129.

The pathogenesis of severe acute respiratory disease syndrome (SARS) is not fully understood. One case-control study has reported an association between susceptibility to SARS and mannan-binding lectin (MBL) in China. As the downstream protein of MBL, variants of the MBL-associated serine protease-2 (MASP2) gene may be associated with SARS coronavirus (SARS-CoV) infection in the same population.

Complement C3 Protein, Bovine, Recombinant (His & SUMO) is expressed in E. coli expression system with N-6xHis-SUMO tag. The predicted molecular weight is 39.5 kDa and the accession number is Q2UVX4.

Factor D cleaves factor B when the latter is complexed with factor C3b, activating the C3bbb complex, which then becomes the C3 convertase of the alternate pathway. Its function is homologous to that of C1s in the classical pathway. Complement factor D Protein, Rat, Recombinant (His & Myc) is expressed in HEK293 mammalian cells with N-10xHis and C-Myc tag. The predicted molecular weight is 29.8 kDa and the accession number is P32038.

May regulate the number of excitatory synapses that are formed on hippocampus neurons. Has no effect on inhibitory synapses.

Non-enzymatic component of C3 and C5 convertases and thus essential for the propagation of the classical complement pathway. Covalently binds to immunoglobulins and immune complexes and enhances the solubilization of immune aggregates and the clearance of IC through CR1 on erythrocytes. Catalyzes the transacylation of the thioester carbonyl group to form ester bonds with carbohydrate antigens.

Complement C2 Protein, Mouse, Recombinant (His) is expressed in HEK293 mammalian cells with His tag. The predicted molecular weight is 84.2 kDa and the accession number is P21180-1.

Complement C5 Protein, Human, Recombinant (Flag) is expressed in HEK293 mammalian cells with Flag tag. The predicted molecular weight is 187.36 kDa and the accession number is NP_001726.2.

Complement Component 1, q subcomponent (C1q) associates with C1r and C1s in order to yield the first component of the serum complement system. Deficiency of C1q has been associated with lupus erythematosus and glomerulonephritis. C1q is composed of 18 polypeptide chains: six A-chains, six B-chains, and six C-chains. Southern blot analysis of chromosomal DNA from vertebrate species demonstrated highest similarity between the C1qB genes, followed by C1qC and finally C1qA. Sequence comparison of C1q from three different species have shown that the B chains have the strongest similarity. C1q was already present at embryonic day 14 (E14) and showed little change in abundance through six weeks postnatal. At E16, C1qB mRNA was present at high abundance in putative microglia macrophages in cortical marginal and intermediate zones, and hippocampal analge.

Complement component C8 is a constituent of the membrane attack complex, C8 alpha, C8 beta and C8G. C8G is a secreted protein and comsists a disulfide-linked C8 alpha-gamma heterodimer and a non-covalently associated C8 beta chain. C8 alpha and C8 beta play an important role in complement-mediated bacterial killing together.C8 is involved in the formation of Membrane Attack Complex on bacterial cell membranes. C8 binds to the C5B-7 complex, forming the C5B-8 complex. C5-B8 binds C9 and acts as a catalyst in the polymerization of C9. The gamma subunit seems to be able to bind retinol. Patients lacking C8 are susceptible to certain bacterial infections.