1qqf
From Proteopedia
N-TERMINALLY TRUNCATED C3D,G FRAGMENT OF THE COMPLEMENT SYSTEM
Structural highlights
Function[CO3_RAT] 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. Acts as a chemoattractant for neutophils. Neutrophil chemotactic factor-2 acts as a chemoattractant for neurophils. Acylation stimulating protein: 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 (By similarity). Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedComplement component C3 plays a key role in the complement-mediated immune defence, and occupies a central position within the complement cascade system. One of its degradation products, C3dg, was purified from rat serum and crystallised in two different crystal forms as N-terminally truncated fragment. Despite the truncation and the lack of a significant portion of the N-terminus as compared to C3d, the structure of the fragment is highly similar to that of recombinant human C3d (Nagar et al., Science 280 (1998) 1277-1281). Structural details of the reactive site have been obtained, suggesting a possible mode of thioester bond formation between Cys-1010 and Gln-1013 and thioester bond cleavage in the transacylation reaction involving His-1126. The truncation at the N-terminus of C3d leads to the exposure of a surface of the molecule that favours dimerisation, so that in both crystal forms, the fragment is present as a dimer, with monomers related by a two-fold axis. Structure at 1.44 A resolution of an N-terminally truncated form of the rat serum complement C3d fragment.,Zanotti G, Bassetto A, Battistutta R, Folli C, Arcidiaco P, Stoppini M, Berni R Biochim Biophys Acta. 2000 May 23;1478(2):232-8. PMID:10825534[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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