The Classical Complement Pathway: Mechanism of Activation of the First Component by Antigen-Antibody Complexes

2015 ◽  
pp. 135-192
Author(s):  
Michael Loos
Keyword(s):  
Complement Pathway ◽  
Classical Complement Pathway ◽  
Antigen Antibody ◽  
Classical Complement

scholarly journals Crystallization and preliminary crystallographic studies of the complement 1qA globular domain from zebrafish,Dare-C1qAgD

2014 ◽  
Vol 70 (7) ◽  
pp. 911-914 ◽  
Author(s):  
Hongyu Yuan ◽  
Rong Chen ◽  
Yanjie Liu ◽  
Mansoor Tariq ◽  
Yaping Sun ◽  
...  
Keyword(s):  
Structural Basis ◽  
Globular Domain ◽  
Immune Functions ◽  
Complement Pathway ◽  
Orthorhombic Space Group ◽  
Cell Parameters ◽  
Classical Complement Pathway ◽  
Reactive Protein ◽  
Antigen Antibody ◽  
Classical Complement

Complement 1q (C1q) is the first component of the complement system which can initiate the classical complement pathway. In human, C1q is composed of 18 polypeptide chains: six C1qA chains, six C1qB chains and six C1qC chains. Each chain has a signal peptide and is comprised of a collagen-like region and a C-terminal C1q globular domain (C1qgD), which is organized as a heterotrimer. C1qgD can recognize antigen–antibody complexes containing IgG and IgM or can bind directly to the C-reactive protein. Although the classical complement pathway is found from fish to mammals, only the human C1qgD structure has been determined. Compared with that of mammals, fish C1q exhibits similar immune functions and genome arrangement. In order to illustrate the structure of C1qgD in fish, zebrafish (Danio rerio) C1qA globular domain (Dare-C1qAgD) was expressed, purified and crystallized. X-ray diffraction data were collected from a crystal to a resolution of 2.05 Å; the crystal belonged to the orthorhombic space groupP212121, with unit-cell parametersa= 50.347,b= 85.059,c= 95.560 Å. It contained three molecules in the asymmetric unit. The Matthews coefficient valueVMwas 2.31 Å3 Da−1, with a calculated solvent content of 46.7%. The data will help to give insight into the structural basis of C1qA in fish species.

scholarly journals Carbamylation of immunoglobulin abrogates activation of the classical complement pathway

2014 ◽  
Vol 44 (11) ◽  
pp. 3403-3412 ◽  
Author(s):  
Catalin Koro ◽  
Ewa Bielecka ◽  
Anders Dahl‐Knudsen ◽  
Jan J. Enghild ◽  
Carsten Scavenius ◽  
...  
Keyword(s):  
Complement Pathway ◽  
Classical Complement Pathway ◽  
Classical Complement
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