The species-specific cell-binding site of the aggregation factor from the sponge Microciona prolifera is a highly repetitive novel glycan containing glucuronic acid, fucose, and mannose

Monoclonal antibodies (McAbs) were raised against the aggregation factor (AF) from the marine sponge Geodia cydonium. Two clones were identified that secrete McAbs against the cell binding protein of the AF complex. Fab fragments of McAbs: 5D2-D11 completely abolished the activity of the AF to form secondary aggregates from single cells. The McAbs were determined to react with the AF in vitro; this interaction was prevented by addition of the aggregation receptor, isolated and purified from the same species. After dissociation of the AF by sodium dodecyl sulfate and 2-mercaptoethanol, followed by electrophoretical fractionation, a 47-kD protein was identified by immunoblotting which interacted with the McAbs: 5D2-D11. During this dissociation procedure, the sunburst structure of the AF was destroyed. In a second approach, the 47-kD protein was isolated by immunoprecipitation; 12 molecules of this protein species were calculated to be associated with the intact AF particle. The 47-kD AF fragment bound to dissociated Geodia cells with a high affinity (Ka of 7 X 10(8) M-1) even in the absence of Ca++ ions; the number of binding sites was approximately 4 X 10(6)/cell. This interaction was prevented by addition of the aggregation receptor to the 47-kD protein in the homologous cell system. Moreover, it was established that this binding occurs species-specifically. The 47-kD fragment of the AF was localized only extracellularly by indirect immunofluorescence staining in cryostat slices. These data suggest that the 47-kD protein is the cell binding molecule of the AF from Geodia.

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Structural Determinants of the Factor IX Molecule Mediating Interaction with the Endothelial Cell Binding Site Are Distinct from Those Involved in Phospholipid Binding

Journal of Biological Chemistry ◽

10.1016/s0021-9258(19)47059-2 ◽

1989 ◽

Vol 264 (34) ◽

pp. 20283-20287

Author(s):

J Ryan ◽

B Wolitzky ◽

E Heimer ◽

T Lambrose ◽

A Felix ◽

...

Keyword(s):

Endothelial Cell ◽

Binding Site ◽

Factor Ix ◽

Cell Binding ◽

Structural Determinants ◽

Phospholipid Binding

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Expression of a developmentally regulated antigen on the surface of skeletal and cardiac muscle cells.

The Journal of Cell Biology ◽

10.1083/jcb.100.6.1977 ◽

1985 ◽

Vol 100 (6) ◽

pp. 1977-1987 ◽

Cited By ~ 41

Author(s):

S J Kaufman ◽

R F Foster ◽

K R Haye ◽

L E Faiman

Keyword(s):

Cell Surface ◽

Cardiac Muscle ◽

Surface Antigen ◽

Cardiac Cells ◽

Cell Surface Antigen ◽

Myoblast Differentiation ◽

Specific Cell ◽

Developmentally Regulated ◽

Cardiac Muscle Cells ◽

Species Specific

H36 is a species-specific, cell-surface antigen on differentiating newborn rat skeletal myoblasts and myogenic lines. This membrane antigen has been defined by a monoclonal antibody raised by the fusion of SP 2/0-Ag14 myeloma cells with spleen cells from mice immunized with myotubes derived from the myogenic E63 line. H36 antigen, isolated by immunoaffinity chromatography, is comprised of two polypeptides with apparent molecular weights of 98,000 and 117,000. Fluorescence photometry and radioimmunoassays have been used to follow quantitative and topographic changes in the H36 determinant during myogenesis. H36 is present at a basal level on replicating myoblasts; it increases on prefusion myoblasts and persists on myotubes. At or near the time of prefusion, it becomes concentrated between adjacent aligned myoblasts and localized on membrane "blebs". H36 is present on both skeletal and cardiac cells but absent from a variety of cells that include fibroblasts, neuronal cells, and smooth muscle. There are approximately 4 x 10(5) determinants per myoblast, and the Ka of the antibody is 3.8 x 10(8) liters/mol. The distributions of H36 on the top and attached surfaces of myoblasts and myotubes are distinct, which suggests localized specialization of these surfaces. H36 is an integral membrane component and upon cross-linking, it associates with the detergent-insoluble cytoskeletal framework. Inhibition of myogenesis by 5-bromodeoxyuridine or by calcium deprivation prevents the developmentally associated changes in the expression of H36. H36 is also absent or markedly reduced on the fu- and Ama102 developmentally defective mutant myoblast lines. We conclude that H36 is a muscle-specific, developmentally regulated cell-surface antigen that may have a role in myoblast differentiation and that can be used to determine the embryonic lineages of skeletal and cardiac muscle.

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Antibody-Targeted Liposomes: Specific Cell Binding and Cytotoxicity

Investigation of Membrane-Located Receptors ◽

10.1007/978-1-4684-4631-9_38 ◽

1984 ◽

pp. 359-359

Author(s):

T. D. Heath ◽

K. Bragman ◽

D. Paphadjopoulos

Keyword(s):

Specific Cell ◽

Cell Binding

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Characterization of a type IV collagen major cell binding site with affinity to the alpha 1 beta 1 and the alpha 2 beta 1 integrins.

The Journal of Cell Biology ◽

10.1083/jcb.113.6.1475 ◽

1991 ◽

Vol 113 (6) ◽

pp. 1475-1483 ◽

Cited By ~ 157

Author(s):

P Vandenberg ◽

A Kern ◽

A Ries ◽

L Luckenbill-Edds ◽

K Mann ◽

...

Keyword(s):

Binding Site ◽

Type Iv Collagen ◽

Cell Attachment ◽

Cell Surface Receptor ◽

Helical Conformation ◽

Amino Acid Residues ◽

Cell Binding ◽

Type Iv ◽

Depth Study ◽

Surface Receptor

The aim of this investigation was to identify the domains of type IV collagen participating in cell binding and the cell surface receptor involved. A major cell binding site was found in the trimeric cyanogen bromide-derived fragment CB3, located 100 nm away from the NH2 terminus of the molecule, in which the triple-helical conformation is stabilized by interchain disulfide bridges. Cell attachment assays with type IV collagen and CB3 revealed comparable cell binding activities. Antibodies against CB3 inhibited attachment on fragment CB3 completely and on type IV collagen to 80%. The ability to bind cells was strictly conformation dependent. Four trypsin derived fragments of CB3 allowed a closer investigation of the binding site. The smallest, fully active triple-helical fragment was (150)3-amino acid residues long. It contained segments of 27 and 37 residues, respectively, at the NH2 and COOH terminus, which proved to be essential for cell binding. By affinity chromatography on Sepharose-immobilized CB3, two receptor molecules of the integrin family, alpha 1 beta 1 and alpha 2 beta 1, were isolated. Their subunits were identified by sequencing the NH2 termini or by immunoblotting. The availability of fragment CB3 will allow for a more in-depth study of the molecular interaction of a short, well defined triple-helical ligand with collagen receptors alpha 1 beta 1 and alpha 2 beta 1.

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