Showing papers by "Michael D. Pierschbacher published in 1982"

Fibronectin: purification, immunochemical properties, and biological activities.

Abstract: Publisher Summary Fibronectin is a cell-surface and blood glycoprotein that apparently mediates adhesion of cells to the extracellular matrix. Malignant cells tend to lack cell surface fibronectin, and this may contribute to their capacity for invasive and metastatic growth. Early isolation methods for plasma fibronectin made use of its propensity to precipitate with fibrinogen and some other proteins when plasma is allowed to stand in the cold. A large fraction of the plasma cryoprecipitate is fibronectin, and it can be purified from such precipitate by using a combination of differential precipitation steps and ion exchange chromatography. Fibronectin from the surface of cultured fibroblasts can be isolated by extraction with low concentrations of urea. Antifibronectin columns can also be used to isolate fibronectin from both plasma and cell cultures. These methods have now largely been replaced by affinity chromatography on gelatin-Sepharose. The methods used in immunochemical quantitation of fibronectin include radioimmunoassay, enzyme immunoassay, and rocket immunoelectrophoresis. Of these methods, enzyme linked immunosorbent assay is probably the most useful one.

Cell attachment on replicas of SDS polyacrylamide gels reveals two adhesive plasma proteins.

Abstract: A novel procedure that detects adhesive proteins in complex mixtures was used to characterize such proteins in plasma The proteins are separated by SDS PAGE and transferred to nitrocellulose filters Cells incubated on these filters attach to those proteins that have adhesive properties When applied to human plasma proteins this procedure reveals, in addition to fibronectin, a cell-attachment protein with a polypeptide molecular weight of 70,000 Using a monoclonal antibody that inhibits attachment of cells to fibronectin, we show that this polypeptide is not a fragment of fibronectin and we present evidence that it is a component of the serum spreading factor Therefore, as defined by our assay, this protein and fibronectin are the major attachment proteins for fibroblastic cells in plasma or serum

Structure of fibronectin and its fragments in electron microscopy.

Abstract: Human plasma fibronectin and a series of its large proteolytic fragments were analyzed by electron microscopy using tungsten shadowing on carbon and polystyrene films. On carbon, intact fibronectin appeared as a randomly coiled strand, while on polystyrene it appeared as an elongated structure. Two fragments of fibronectin, Mr=205000 and 190000, which lack the NH2-terminal domain of fibronectin and retain the collagen-binding, cell-attachment and heparin-binding functions, and a Mr= 170000 fragment, which retains the collagen-binding and cell-attachment functions, were seen as rods with varying degrees of nodularity while a Mr= 100000 fragment, which only binds to collagen, had two clear-cut domains. These results support the existing biochemical evidence that the segregation of the functional activities in the fibronectin molecule is based on distinct structural domains and provides evidence for the existence of an additional structural domain not revealed by biochemical and functional studies.