It has long been appreciated that, for many types of cells, attachment to a substrate is required for their replication. Collagen substrates enhance the growth (64, 70, 109, 238) as well as the differentiation (40, 69, 85, 86, 146, 161, 184), of many cells in culture above that observed with other substrates such as plastic and glass. As discussed in this report, many cultured cells including fibroblasts, myoblasts, hepatocytes, chondrocytes, and certain epithelial cells are thought not to bind directly to the collagen substrate or to the plastic surface of culture dishes (31, 73, 74, 76, 77, 89, 93, 113, 164, 220) . Instead, extracellular glycoproteins bind the cells to the substrate. One of these attachment proteins, fibronectin, has been extensively studied (99, 151, 166, 227, 228, 244) . Fibronectin is produced by fibroblasts (13, 197, 246) and endothelial cells (102, 140) as well as some other cell types . It is also present in high concentrations in blood and serum (152) . In culture, serum fibronectin, as well as that produced by the cells, can bind to both the collagen substrates and the tissue culture plastic surface and mediate the attachment of cells (73, 113, 164, 242) . Circulating fibronectin participates in a variety of reactions important to wound healing, including the adhesion and spreading of platelets on collagen (10, 14, 75, 100, 204), binding to the fibrin clot (74, 150, 198) and to collagen (37, 46, 94, 103, 119), promoting opsonization reactions by phagocytic cells (18, 94, 201), and promoting fibroblast migration (6, 61) . Thus, fibronectin not only functions as an attachment protein, but also may play an important role in repair reactions . In the case of certain differentiated cells, such as chondrocytes (89) and epithelial cells (159, 220), glycoproteins different from fibronectin are active in attachment. The components of these extracellular matrices of fibroblasts, chondrocytes, and epithelial cells differ with the cell type, and they require separate attachment proteins to provide additional specificity to the interaction ofthe cell with its matrix. Alterations in cellsubstratum interactions are observed in differentiating cells and after spontaneous transformation of cells or exposure to oncogenic agents (99, 228) . This review will briefly outline our current knowledge of the types of collagen and their distribution and biosynthesis. Then, the interaction of cells with colREVIEW

/pdf/role-of-collagenous-matrices-in-the-adhesion-and-growth-of-3g3jaytqg4.pdf

Role of collagenous matrices in the adhesion and growth of cells.

Plant phenolic compounds and the isolation of plant enzymes

https://www.cell.com/biophysj/pdf/S0006-3495(04)73889-8.pdf

The Hydrodynamic Radii of Macromolecules and Their Effect on Red Blood Cell Aggregation

Engineering biocompatible implant surfaces

Molecular biology of fibronectin.

Fibronectin of human plasma associated readily with denatured collagen but gave only a weak reaction with the native protein. In the presence of heparin, however, solutions of native collagen type III, and fibronectin produced precipitates at an ionic strength of 0.2. In the presence of fibronectin and optimal additions of heparin, up to 60% of soluble native 125I-collagen type III, but only about 10% of native 125I-collagen type I, were insolubilized. Heparin also enhanced the formation of insoluble complexes from fibronectin and denatured collagen type I and type III. In the absence of collagen 125I-fibronectin was partially precipitated by heparin. Electron micrographs showed filamentous structures. Collagen did not increase the amount of 125I-fibronectin precipitated by heparin unless a critical collagen concentration was exceeded. It is suggested that heparin induced the transition of fibronectin from a globular to an elongated form, capable of forming filamentous precipitates which adsorb native collagen. Hyaluronic acid and putrescine prevented the insolubilization of native collagen type III, by fibronectin and heparin.

Fibronectin (cold-insoluble globulin), VI. Influence of heparin and hyaluronic acid on the binding of native collagen.

Fibronektin, fruher auch LETS-Protein genannt, ist ein hochmolekularer Eiweiskorper (Mol-Gew. ca. 450 000), welcher im perizellularen Bereich von Fibroblasten und anderen adharenten Zellen aber auch sonst im Bindegewebe in Form dunner Fibrillen auftritt. Eine losliche Form, die mit dem Oberflachenprotein der Zellen immunologisch identisch und chemisch zumindest sehr ahnlich ist, kommt im Blutplasma in einer Konzentration von etwa 300 µg/ml vor. Sie wird auch als Kalte-unlosliches Globulin bezeichnet. Fibronektin besitzt Affinitat zu Zelloberflachen und zu verschiedenen Matrixsubstanzen wie Fibrin und Kollagen und vermittelt dadurch das Anhaften von Zellen an diese Substrate. Es wirkt auserdem als Opsonin fur die Phagozytose gelatinehaltiger Verbindungen und ist vermutlich wichtig fur die Ausschleusung von loslichem Fibrin aus dem Blutkreislauf durch das retikulo-endotheliale System. Auch Bakterienoberflachen werden von Fibronektin erkannt. Eine Umwandlung von loslichem Fibronektin in Fibrillen gelingt mit Heparin, das gleichzeitig die Bindung von loslichem Fibronektin an die Zellen verstarkt. Heparin oder, wie vermutet wird, das an Oberflachen verschiedener Zellen vorhandene Heparansulfat scheinen somit als Cofaktoren fur die Ausbildung der perizellularen Fibrillen wesentlich zu sein. Die mit Heparin abgeschiedenen Fibronektinfibrillen weisen auch eine bessere Affinitat zu nativem Kollagen, besonders zu Typ III, auf als losliches Fibronektin. Als Antagonist wirkt Hyaluronsaure, die in hoheren Konzentrationen die Wechselwirkung der Fibronektinfibrillen mit Kollagen und Zelloberflachen verhindert. Auch sulfatierte Proteoglykane aus Knorpelgewebe maskieren Fibronektinfibrillen. Virus-transformierte Fibroblasten erzeugen weniger Fibronektin und vermogen perizellulare Fibrillen nur schlecht festzuhalten. Eine Erklarung dafur konnte die erhohte Abscheidung von Hyaluronsaure sein. Die transformierten Zellen haften nur schlecht an einer Unterlage und weisen im Gegensatz zu gesunden eine runde Form auf. Dieser Phanotyp kann durch Fibronektin zum grosten Teil korrigiert werden. Es wird vermutet, das Fibronektin auch auf die Bildung von Bindegewebe Einflus nimmt, indem es kollagene Vorstufen an der Oberflache von Fibroblasten akkumuliert und dadurch die Fibrillogenese beeinflust.

Fibronectin--mediator between cells and connective tissue.

Fibronektin, fruher auch LETS-Protein genannt, ist ein hochmolekularer Eiweiskorper (Mol-Gew. ca. 450 000), welcher im perizellularen Bereich von Fibroblasten und anderen adharenten Zellen aber auch sonst im Bindegewebe in Form dunner Fibrillen auftritt. Eine losliche Form, die mit dem Oberflachenprotein der Zellen immunologisch identisch und chemisch zumindest sehr ahnlich ist, kommt im Blutplasma in einer Konzentration von etwa 300 µg/ml vor. Sie wird auch als Kalte-unlosliches Globulin bezeichnet. Fibronektin besitzt Affinitat zu Zelloberflachen und zu verschiedenen Matrixsubstanzen wie Fibrin und Kollagen und vermittelt dadurch das Anhaften von Zellen an diese Substrate. Es wirkt auserdem als Opsonin fur die Phagozytose gelatinehaltiger Verbindungen und ist vermutlich wichtig fur die Ausschleusung von loslichem Fibrin aus dem Blutkreislauf durch das retikulo-endotheliale System. Auch Bakterienoberflachen werden von Fibronektin erkannt.

Fibronektin — Mittler zwischen Zellen und Bindegewebe

Resolution of a cathepsin D digest of plasma fibronectin on heparin-Sepharose yielded, in addition to non-bound and weakly retained material (Fraction I and II), various fragments which were not eluted until 0.25M NaCl (Fraction III) and 0.5M NaCl (Fraction IV) was applied. Fraction III contained predominantly a peptide of Mr 70 000 originating from the N-terminus of the fibronectin subunits as well as high molecular weight precursors yielding the Mr 70 000 peptide by further digestion. All those peptides were retained by immobilized denatured collagen, type I, indicating the presence of the known gelatin-binding domain. In addition, they contained a transamidase-sensitive site as revealed from a digest of fibronectin previously labelled with [14C]putrescine by a transamidase-mediated reaction. Plasminolysis of the fragment of Mr 70 000 resulted in two peptides of Mr 30 000 and 40 000, only the former being retained by heparin-Sepharose. Fraction IV contained a fragment of Mr 140 000 which, after reduction, dissociated into two peptides of Mr 75 000 and 65 000. Apparently, it included the disulfide bond(s) connecting the two fibronectin subunits close to their C-terminal ends. Partial digestion of the two electrophoretically separated peptide chains with protease of Staphylococcus aureus V8 yielded for each chain a number of peptides with equal electrophoretic migration rate. In addition, however, some peptides were different in the two digests. The results were consistent with an identical or homologous structure of the two peptide chains with an additional sequence in the longer chain. The latter (Mr 75 000) uniquely contained a transamidase susceptible site as demonstrated by processing of [14C]putrescine-labelled fibronectin.

Location of Heparin-Binding Sites of Fibronectin. Detection of a hitherto Unrecognized Transamidase Sensitive Site

Shape, conformation and stability of fibronectin fragments determined by electron microscopy, circular dichroism and ultracentrifugation

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