Related Experiment Video
Updated: May 3, 2026

Modified Yeast-Two-Hybrid System to Identify Proteins Interacting with the Growth Factor Progranulin
Published on: January 17, 2012
Properdin anc C3 proactivator: alternate pathway components in human glomerulonephritis
Abstract:
Serological and immunopathological studies of human glomerulonephritis have suggested that alternate pathways of activation of the third component of complement may be important in some forms of glomerulonephritis. We have investigated the role of two alternate pathway proteins, properdin and C3 proactivator, in 22 patients with chronic membranoproliferative glomerulonephritis, 21 patients with systemic lupus erythematosus, 20 patients with acute poststreptococcal glomerulonephritis, and 19 patients with other forms of renal disease. C3 (measured at beta(1)A), properdin, and C3 proactivator were assayed by single radial immunodiffusion. In sera with low beta(1)A (< 2 SD), mean properdin was most significantly decreased in patients with acute poststreptococcal glomerulonephritis but was also significantly decreased in chronic membranoproliferative glomerulonephritis and in untreated systemic lupus erythematosus. Properdin levels in other renal disease, acute glomerulonephritis, and chronic membranoproliferative glomerulonephritis with normal beta(1)A levels were not significantly different from normal. A positive correlation between beta(1)A and properdin levels in individual sera was present in all diseases except systemic lupus erythematosus. Serum C3 proactivator was markedly decreased in active systemic lupus erythematosus and there was a positive correlation between beta(1)A and C3 proactivator levels in systemic lupus erythematosus and other renal diseases but not acute poststreptococcal glomerulonephritis. Properdin in fresh sera from four patients with systemic lupus erythematosus and five with chronic membranoproliferative glomerulonephritis showed increased migration toward the cathode on immunoelectrophoresis, suggesting in vivo change of the properdin molecule. The observation of reduced serum levels of properdin and C3 proactivator and altered electrophoretic migration of properdin in some patients with glomerulonephritis provide new evidence for participation of these alternate pathway proteins in glomerulonephritis.
More Related Videos
Related Concept Videos
Formation of the Platelet Plug
As the injured blood vessel contracts, endothelial cells undergo contraction, revealing collagen fibers in the basement membrane and underlying connective tissue. Furthermore, the plasma membrane of endothelial cells becomes adhesive, preparing the site for platelet adhesion. Platelets...
Extrinsic and Intrinsic Pathways of Hemostasis
The Extrinsic Pathway
The extrinsic pathway of coagulation is typically initiated by tissue damage that exposes blood to tissue factor (TF), a protein released by the damaged tissue cells outside the blood vessels—this interaction with TF triggers biochemical reactions involving specific clotting factors. The key player here is Factor VII, which...
Clot Retraction and Fibrinolysis
Complement System
Acute Inflammation I: Cellular Phase
Acute Inflammation II: Local and Systemic Effects

