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Rabbit Anti-Complement C3b alpha' chain/FITC Conjugated antibody
background:
The complement factor C3 consists of an alpha and a beta chain. C3 is a central factor in the complement cascade. It is central to the alternative pathway that leads to the C3 convertase C3bBb. The classical mannose binding lectin activation pathway leads to the C3 convertase C4b2a. These convertases cleave C3 resulting in C3a and C3b. Further degradation leads to the formation of the alpha chain products C3d, C3g and C3c. C3 is an acute phase protein that is produced by a wide range of tissues, including renal epithelial cells and hepatocytes.
Function:
C3 plays a central role in the activation of the complement system. Its processing by C3 convertase is the central reaction in both classical and alternative complement pathways. After activation C3b can bind covalently, via its reactive thioester, to cell surface carbohydrates or immune aggregates.
Derived from proteolytic degradation of complement C3, C3a anaphylatoxin is a mediator of local inflammatory process. It induces the contraction of smooth muscle, increases vascular permeability and causes histamine release from mast cells and basophilic leukocytes.
Acylation stimulating protein (ASP): adipogenic hormone that stimulates triglyceride (TG) synthesis and glucose transport in adipocytes, regulating fat storage and playing a role in postprandial TG clearance. Appears to stimulate TG synthesis via activation of the PLC, MAPK and AKT signaling pathways. Ligand for GPR77. Promotes the phosphorylation, ARRB2-mediated internalization and recycling of GPR77.
Subunit:
C3 precursor is first processed by the removal of 4 Arg residues, forming two chains, beta and alpha, linked by a disulfide bond. C3 convertase activates C3 by cleaving the alpha chain, releasing C3a anaphylatoxin and generating C3b (beta chain + alpha' chain). C3dg interacts with CR2 (via the N-terminal Sushi domains 1 and 2). During pregnancy, C3dg exists as a complex (probably a 2:2:2 heterohexamer) with AGT and the proform of PRG2. Interacts with VSIG4. C3b interacts with herpes simplex virus 1 (HHSLV1) and herpes simplex virus 2 (HHSLV2) envelope glycoprotein C; this interaction inhibits the activation of the complement system. Interacts with S.aureus immunoglobulin-binding protein sbi, this prevents interaction between C3dg and CR2. Interacts with S.aureus fib.
Subcellular Location:
Secreted.
Tissue Specificity:
Plasma. The acylation stimulating protein (ASP) is expressed in adiopocytes and released into the plasma during both the fasting and postprandial periods.
Post-translational modifications:
C3b is rapidly split in two positions by factor I and a cofactor to form iC3b (inactivated C3b) and C3f which is released. Then iC3b is slowly cleaved (possibly by factor I) to form C3c (beta chain + alpha' chain fragment 1 + alpha' chain fragment 2), C3dg and C3f. Other proteases produce other fragments such as C3d or C3g. C3a is further processed by carboxypeptidases to release the SLCterminal arginine residue generating the acylation stimulating protein (ASP). Levels of ASP are increased in adipocytes in the postprandial period and by insulin and dietary chylomicrons.
Phosphorylation sites are present in the extracellular medium.
DISEASE:
Defects in C3 are the cause of complement component 3 deficiency (C3D) [MIM:613779]. A rare defect of the complement classical pathway. Patients develop recurrent, severe, pyogenic infections because of ineffective opsonization of pathogens. Some patients may also develop autoimmune disorders, such as arthralgia and vasculitic rashes, lupus-like syndrome and membranoproliferative glomerulonephritis.
Genetic variation in C3 is associated with susceptibility to age-related macular degeneration type 9 (ARMD9) [MIM:611378]. ARMD is a multifactorial eye disease and the most common cause of irreversible vision loss in the developed world. In most patients, the disease is manifest as ophthalmoscopically visible yellowish accumulations of protein and lipid that lie beneath the retinal pigment epithelium and within an elastin-containing structure known as Bruch membrane.
Similarity:
Contains 1 anaphylatoxin-like domain.
Contains 1 NTR domain.
Database links:
Entrez Gene: 718 Human
Omim: 120700 Human
SwissProt: P01024 Human
Important Note:
This product as supplied is intended for research use only, not for use in human, therapeutic or diagnostic applications.
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