Basement membrane collagen of renal glomerulus

Characterization of a 130,000-dalton glycoprotein isolated from pulmonary secretions of patients with alveolar proteinosis

A new glycoprotein with an apparent molecular weight of 130,000 was isolated, purified, and partially characterized from the pulmonary secretions which accumulate so massively in the lungs of patients suffering from pulmonary alveolar proteinosis. The amino acid analysis of the glycoprotein showed the presence of relatively high amounts of glycine, glutamic acid, aspartic acid, leucine, and valine, and small amounts of hydroxyproline, but no hydroxylysine. It contains approximately 6% hexose, 3% sialic acid, and 4% glucosamine. The neutral sugars are galactose, mannose, and fucose. This alveolar glycoprotein cross-reacted with an antiserum prepared in rabbits against a larger glycoprotein (250,000 mol wt) isolated from the same source, suggesting that the larger alveolar glycoprotein may be the precursor of the smaller one.

Isolation and characterization of a native placental basement-membrane collagen and its component alpha chains

Native type IV collagen was isolated from human placenta using pepsin solubilisation followed by fractional salt precipitation and chromatogarphic purification. The native preparation was characterised using amino acid analyses, disc gel electrophoresis, segment-long-spacing crystallites and immunological methods. Two component alpha chains were isolated with molecular weights of approximately 95000 and 70000. Cyanogen bromide digests of these chains indicated that they are not related to any of the known alpha chains of interstitial collagens or to the recently described collagen containing alphaA and alphaB chains. They are also not related to one another and are therefore probably fragments of two genetically distinct type IV collagen alpha chains.

X-ray diffraction study of bovine lens capsule collagen

The wide angle X-ray diffraction pattern of air-dried lens capsule collagen under tension is the same as the tendon collagen diffraction pattern with regard to the main reflections, and indicates that lens capsule collagen has the characteristic three-stranded helical structure with an axial repeat of 0.29 nm as tendon collagen. The low angle X-ray diffraction pattern shows several weak diffraction maxima corresponding to the meridional reflections of capsule collagen which show orders of 63.0 nm periodicity. This is an evidence of quarter staggered molecular assembly typical of tendon collagen even if less ordered. The results are consistent with the existence in lens capsule collagen of clearly defined molecular units, which can be oriented by stress and are packed in a poor-ordered fibrillar assembly.

Collagen synthesis by human glomerular cells in culture

Collagen synthesis was studied in three subcultured human glomerular cell types, by radiolabeled incorporation of [14C]proline and [3H]lysine. The epithelioid circular glomerular cells secrete a collagen with a single size of chain (possibly type IV) with a high ratio of hydroxyproline to proline, hydroxylysine to lysine, and 11--17% of hydroxyproline as the 3-isomer. The smooth muscle-like rhomboid glomerular cells secrete collagen with a chain pattern suggesting types III and I collagen, distinct from that found in the media of fibroblasts. Small ovoid glomerular cells are morphologically and biochemically intermediate between circular glomerular cells and rhomboid glomerular cells, and may represent an in vitro modification of either circular glomerular cells or rhomboid glomerular cells.

Glomerular basement membrane collagen and activities of the intracellular enzymes of collagen biosynthesis in congenital nephrotic syndrome of the Finnish type

The composition of pepsin-solubilized glomerular basement membrane (GBM) collagen was studied in kidneys from patients with congenital nephrotic syndrome of the Finnish type (CNF). The 3-hydroxyproline content in the GBM collagen in CNF was only about one half of that noted in the controls. The alanine content was slightly higher in CNF, but no differences were found in the contents of the other amino acids or carbohydrates. Analysis of the GBM collagen by sodium dodecyl sulphate polyacrylamide gel electrophoresis after reduction indicated a lower proportion of one of the major polypeptide chains in CNF than in the controls, while a higher proportion of one low molecular weight minor component was noted. The activities of the five intracellular enzymes of collagen biosynthesis, including prolyl 3-hydroxylase, were not significancy altered in the CNF kidney cortex samples when compared with the controls.

Large scale preparation of bovine renal glomerular basement membrane in the presence of protease inhibitors

A method is described for the isolation of large quantities of basement membrane from bovine renal glomeruli under conditions which minimize or prevent degradation by tissue-associated proteases. The method incorporates the use of moderately-high concentrations of the protease inhibitors: ethylenediamine tetraacetic acid, epsilon-amino caproic acid, N-ethymaleimide, and diisopropylfluorophosphate; and the maintenance of a temperature of 0-4 degrees C throughout the procedure. Glomeruli preparations are isolated by a modified sieving technique and are routinely of purity greater than 97%. Under optimum conditions, three to four grams of basement membrane can be isolated under safe and rapid conditions in one week.

Biochemical characteristics and biological significance of the genetically-distinct collagens

In recent years it has become evident that genetic polymorphism is dramatically expressed in the structural protein, collagen. Current information on the biochemical properties, biosynthesis, and tissue distribution of Type I, II, and III collagens is summarized with special reference to possible unique functional roles fulfilled by each of these collagens.

Studies on the sulfhydryl groups in type III collagen

The Type III collagen molecule, [alpha](III)]3, is comprised of three alphal(III) chains each of which contains two cysteinyl residues. Free sulfhydryl groups, however, could not be detected in the denatured, trimeric gamma-component of Type III collagen as judged by the failure to form derivatives with the alkylating reagents iodo-[14C]acetic acid and 4-vinylpyridine. This absence of sulfhydryl group reactivity did not appear to result from disulfide-binding between Type III collagen and noncollagenous peptides. Collectively, the results indicate that all of the six sulfhydryl groups of the Type III collagen molecule participate in interchain disulfide-bonding.