Amyloid P-component is a constituent of normal human glomerular basement membrane.
Glomerular and other vascular basement membranes were found to contain an antigen that was immunochemically indistinguishable from serum amyloid P-component. There was no immunological cross-reactivity between antisera to serum amyloid P-component and to collagen types I, III, IV, or V. The amyloid P-component antigen was confined to the endothelial aspect, the lamina rara interna, of glomerular basement membrane. It could not be eluted by high-ionic-strength saline, EDTA, dithiothreitol, or either polar or nonpolar detergents, but was released into solution when isolated glomerular basement membrane was digested by highly purified bacterial collagenase. Most of these P-component molecules and their constituent polypeptide chains were of higher molecular weight and lower isoelectric point than serum amyloid P-component. These findings indicate that, as well as being a normal plasma protein and a universal constituent of amyloid deposits, P-component is also a normal matrix glycoprotein of basement membrane in which it is covalently linked to collagen and/or other matrix proteins. This may be relevant both to the pathogenesis of amyloidosis and to other aspects of physiology and pathology of basement membranes.
D000682:Amyloid / Q000276:immunology*; D000686:Amyloidosis / Q000276:immunology; D001485:Basement Membrane / Q000276:immunology*; D005455:Fluorescent Antibody Technique; D006801:Humans; D007123:Immunoelectrophoresis, Two-Dimensional; D007124:Immunoenzyme Techniques; D007678:Kidney Glomerulus / Q000276:immunology*
D000682:Amyloid