Search results for "C3b"

Genetic polymorphism of human complement factor I (C3b inactivator) in the Chinese Han population.

1999

The human complement factor I (IF) polymorphism has been analysed by polyacrylamide gel isoelectric focusing electrophoresis of neuraminidase-treated EDTA plasma samples followed by immunoblotting and enzymatic detection. In a population study among 121 random individuals from Chengdu, PR China, three different common phenotypes were observed. The results show that IF is polymorphic in the Chinese population. The allele frequencies were as follows: FI*A = 0.153, FI*B = 0.847. The distribution of observed phenotypes was in accordance with the Hardy-Weinberg equilibrium. In comparison to other Asian population studies, the frequency of the IF*A allele was the highest in the Chinese population…

Combined homozygous factor H and heterozygous C2 deficiency in an Italian family

1988

Three of four children in a family have homozygous (less than 1% of normal) deficiency of factor H of the complement system and both parents, who are first cousins, are heterozygous for the same defect. The father and two of the H-deficient siblings also have a partial C2 deficiency. One of the children with combined deficiencies is affected by systemic lupus erythematosus with nephritis. No increased susceptibility to infections has been observed in the family. H deficiency is inherited in an autosomal codominant manner and is independently transmitted from C2 deficiency and HLA haplotypes. In the homozygous state it is associated with very low serum concentrations of B and C3, barely demo…

Opsonizing activities of IgG, IgM antibodies and the C3b inactivator-cleaved third component of complement in macrophage phagocytosis

1976

Phagocytosis of SRBC by guinea-pig peritoneal macrophages is enhanced by opsonizing IgG antibody alone. IgM antibody requires the presence of bound C3. Treatment of C3b coated SRBC with purified C3b inactivator (yielding EAIgM C1423d) does not reduce attachment to, and phagocytosis by, peritoneal macrophages. This finding suggests the existence of a C3d receptor on peritoneal macrophages. EC43b intermediates which have been produced by removing IgM antibody by mercaptoethanol treatment and by subsequent removal of C1 and C2, are phagocytosed despite the absence of IgM antibody. Furthermore, treatment of EC43b with C3b inactivator does not change phagocytosis. Thus, IgM antibody does not app…

Complement components in relation to macrophage function

1983

Computational methodologies applied to Protein-Protein Interactions for molecular insights in Medicinal Chemistry

2021

In living systems, proteins usually team up into “molecular machinery” implementing several protein-to-protein physical contacts – or protein-protein interactions (PPIs) – to exert biological effects at both cellular and systems levels. Deregulations of protein-protein contacts have been associated with a huge number of diseases in a wide range of medical areas, such as oncology, cancer immunotherapy, infectious diseases, neurological disorders, heart failure, inflammation and oxidative stress. PPIs are very complex and usually characterised by specific shape, size and complementarity. The protein interfaces are generally large, broad and shallow, and frequently protein-protein contacts are…

Effects of hydrocortisone on binding of IgG or C3b-coated erythrocytes to human monocytes and polymorphonuclear leucocytes.

1979

Suppressive effects of C3b on monocyte-dependent T cell proliferation.

1987

The effect of C3b treatment of human monocytes on secondary antigen-dependent T cell response was studied. When antigen-specific T cell blasts were cultivated together with C3b-treated monocytes the proliferative response was inhibited in a dose-dependent fashion. This suppressive effect was specific for C3b because heat-inactivated C3b or buffer alone had no influence on T cell proliferation. In part, this suppressive effect is mediated through a C3b-induced decreased expression of class II antigens on the surface of treated monocytes, but another suppressive mechanism exists because the C3b pretreatment of monocytes also led to an inhibition of the proliferative response in a class II ant…

Autophagy

2012

Klionsky, Daniel J. et al.

Novel Insights into the Cellular Localization and Regulation of the Autophagosomal Proteins LC3A, LC3B and LC3C

2020

Macroautophagy is a conserved degradative process for maintaining cellular homeostasis and plays a key role in aging and various human disorders. The microtubule-associated protein 1A/1B light chain 3B (MAP1LC3B or LC3B) is commonly analyzed as a key marker for autophagosomes and as a proxy for autophagic flux. Three paralogues of the LC3 gene exist in humans: LC3A, LC3B and LC3C. The molecular function, regulation and cellular localization of LC3A and LC3C have not been investigated frequently, even if a similar function to that described for LC3B appears likely. Here, we have selectively decapacitated LC3B by three separate strategies in primary human fibroblasts and analyzed the evoked e…

Analysis of complement C3 activation products in human atherosclerotic lesions.

1991

Abstract Cleavage of the complement C3 protein is essential for complement activation. Saline extracts of human atherosclerotic lesions were examined by various techniques for the presence of C3 cleavage fragments. Crossed intermediate gel immunoelectrophoresis revealed that native C3 was the predominate C3 protein in extracts and that the C3dg fragment was also detected. SDS-PAGE/ Western blot analyses of lesion extracts employing monoclonal antibodies directed at C3c and C3dg fragment determinants demonstrated molecular weight bands corresponding to the known molecular weights of all the physiologic C3 cleavage fragments, except Cab which is known to have a short half-life. After C3, the …