scholarly journals Identification of the Arg-Gly-Asp sequence in laminin A chain as a latent cell-binding site being exposed in fragment P1

FEBS Letters ◽  
1990 ◽  
Vol 262 (1) ◽  
pp. 82-86 ◽  
Author(s):  
Monique Aumailley ◽  
Martin Gerl ◽  
Amoud Sonnenberg ◽  
Rainer Deutzmann ◽  
Rupert Timpl
Keyword(s):  
Binding Site ◽  
Cell Binding ◽  
A Chain

scholarly journals Recognition of the laminin E8 cell-binding site by an integrin possessing the alpha 6 subunit is essential for epithelial polarization in developing kidney tubules.

1990 ◽  
Vol 111 (3) ◽  
pp. 1265-1273 ◽  
Author(s):  
L Sorokin ◽  
A Sonnenberg ◽  
M Aumailley ◽  
R Timpl ◽  
P Ekblom
Keyword(s):  
Epithelial Cells ◽  
Binding Site ◽  
Apical Cell ◽  
Cell Types ◽  
Metanephric Mesenchyme ◽  
Kidney Tubule ◽  
Cell Binding ◽  
Developing Kidney ◽  
A Chain ◽  
Integrin Alpha 6

It has been previously shown that A-chain and domain(E8)-specific antibodies to laminin that inhibit cell adhesion also interfere with the establishment of epithelial cell polarity during kidney tubule development (Klein, G., M. Langegger, R. Timpl, and P. Ekblom. 1988. Cell. 55:331-341). A monoclonal antibody specific for the integrin alpha 6 subunit, which selectively blocks cell binding to E8, was used to study the receptors involved. Immunofluorescence staining of embryonic kidneys and of organ cultures of metanephric mesenchyme demonstrated coappearance of the integrin alpha 6 subunit and the laminin A-chain in regions where nonpolarized mesenchymal cells convert into polarized epithelial cells. Both epitopes showed marked colocalization in basal areas of tubules, while an exclusive immunostaining for alpha 6 was observed in lateral and apical cell surfaces of the tubular epithelial cells. Organ culture studies demonstrated a consistent inhibition of kidney epithelium development by antibodies against the alpha 6 subunit. The data suggest that the recognition of E8 cell-binding site of laminin by a specific integrin is crucial for the formation of kidney tubule epithelium from undifferentiated mesenchymal stem cells. In some other cell types (endothelium, some ureter cells) an exclusive expression of alpha 6 with no apparent colocalization of laminin A-chain in the corresponding basement membrane was seen. Thus, in these cells, integrins possessing the alpha 6 subunit may bind to laminin isoforms that differ from those synthesized by developing tubules.

scholarly journals 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.

1991 ◽  
Vol 113 (6) ◽  
pp. 1475-1483 ◽  
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.

Differential expression of laminin A and B chains during development of embryonic mouse organs

Development ◽  
1990 ◽  
Vol 110 (3) ◽  
pp. 823-837 ◽  
Author(s):  
G. Klein ◽  
M. Ekblom ◽  
L. Fecker ◽  
R. Timpl ◽  
P. Ekblom
Keyword(s):  
Cell Types ◽  
Northern Blotting ◽  
Basement Membranes ◽  
Mouse Tumor ◽  
Cell Binding ◽  
Embryonic Mouse ◽  
Developing Heart ◽  
Epithelial Sheets ◽  
A Chain ◽  
Polypeptide Chains

Laminin is a large glycoprotein of basement membranes. The best described laminin from a mouse tumor contains three polypeptide chains (A, B1 and B2), but there is recent evidence that some cell types produce laminin isoforms lacking the A chain. We have here studied the occurrence of the isoforms during mouse organogenesis. In all tissues studied, the A chain mRNA and polypeptide were more weakly expressed than those of the B chains. Laminin A chain polypeptides showed a much more restricted tissue distribution than the B chains. Laminin A chain polypeptide was mainly detected in basement membranes of epithelial cells, suggesting that this chain is important for morphogenesis of epithelial sheets. Most endothelial basement membranes and all embryonic mesenchyme matrices studied seemed to lack the A chain even though they contained B chains. Several of the cells producing laminin devoid of A chain seem to produce other polypeptides that become complexed to the B chains. With an anti-laminin antiserum, which in immunoblots reacts only with A and B polypeptide chains, additional polypeptides of 160 and 190 × 10(3) Mr were co-precipitated from all tissues studied. In developing heart, a polypeptide of 300 × 10(3) Mr was co-precipitated in addition. Our data suggest that these laminin-associated polypeptides are not formed by a differential splicing of the known A chain mRNA. Northern blotting of poly (A)+ RNA showed only 10kb A chain transcripts but no truncated forms. We conclude that several cell types in the mouse embryo produce laminin variants that lack the 400 × 10(3) Mr A chain. Since a major cell binding site of laminin contains parts of the A chain, the variants should differ in biological function from laminin containing this A chain.

scholarly journals Kinetic studies on the effect of heparin and fibrin on plasminogen activators

1988 ◽  
Vol 249 (1) ◽  
pp. 77-81 ◽  
Author(s):  
R Fears
Keyword(s):  
Binding Site ◽  
Chondroitin Sulphate ◽  
Kinetic Studies ◽  
Model Systems ◽  
Tissue Type ◽  
Type Plasminogen Activator ◽  
Pentosan Polysulphate ◽  
A Chain ◽  
Activator Complex

1. Possible interactions between fibrin(ogen) and heparin in the control of plasminogen activation were studied in model systems using the thrombolytic agents tissue-type plasminogen activator (t-PA), urokinase and streptokinase.plasminogen activator complex and the substrates Glu- and Lys-plasminogen. 2. Both t-PA and urokinase activities were promoted by heparin and by pentosan polysulphate, but not by chondroitin sulphate or hyaluronic acid. The effect was on Km. 3. In the presence of soluble fibrin (and its mimic, CNBr-digested fibrinogen) the effect of heparin on t-PA was attenuated, although not abolished. In studies using a monoclonal antibody and 6-aminohexanoic acid, it was found that heparin and fibrin did not seem to share a binding site on t-PA. 4. The activity of t-PA B-chain was unaffected by heparin, so the binding site is located on the A-chain of t-PA (and urokinase). 5. Fibrin potentiated the activity of heparin on urokinase. The activity of streptokinase.plasminogen was unaffected by heparin whether or not fibrin was present. 6. If these influences of heparin and fibrin also occur in vivo, then, in the presence of heparin, the relative fibrin enhancement of t-PA will be diminished and the likelihood of systemic activation by t-PA is increased.

scholarly journals Localization of sites through which C-reactive protein binds and activates complement to residues 14-26 and 76-92 of the human C1q A chain.

1992 ◽  
Vol 175 (5) ◽  
pp. 1373-1379 ◽  
Author(s):  
H Jiang ◽  
F A Robey ◽  
H Gewurz
Keyword(s):  
Amino Acids ◽  
Binding Site ◽  
Immunoglobulin G ◽  
Inhibitory Activity ◽  
Sequence Specificity ◽  
C Reactive Protein ◽  
Reactive Protein ◽  
Binding Regions ◽  
A Chain ◽  
A Charge

Studies were initiated to localize the C-reactive protein (CRP) binding site on the collagen-like region (CLR) of C1q. CRP bound preferentially to the A chain of reduced C1q, in contrast to aggregated immunoglobulin G (Agg-IgG), which reacted preferentially with the C chain. A group of C1q A chain peptides, including peptides identical to residues 81-97, 76-92, and 14-26, respectively, were synthesized from predicted binding regions. Peptide 76-92 contained two proximal lysine groups, and peptide 14-26 contained four proximal arginine groups. CRP-trimers and CRP-ligand complexes did not bind to immobilized peptide 81-97, but bound avidly to immobilized peptides 76-92 and 14-26. Agg-IgG did not bind to any of the peptides. Peptide 76-92 partially, and peptide 14-26 completely, inhibited binding of CRP to intact C1q. Peptide 14-26 also blocked C consumption initiated by CRP, but not by IgG. Replacement of the two prolines with alanines, or scrambling the order of the amino acids, resulted in loss of ability of peptide 14-26 to inhibit C1q binding and C activation by CRP, indicating a sequence specificity, and not a charge specificity alone, as the basis for the inhibitory activity of the peptide. Similar investigations with scrambled peptides showed a sequence specificity for the effects of peptide 76-92 as well. DNA and heparin inhibited binding of CRP trimers to intact C1q, as well as to each peptide 14-26 and 76-92, suggesting involvement of these regions in C1q-CLR binding reactions generally. Collectively, these data identify two cationic regions within residues 14-26 and 76-92 of the C1q A chain CLR as sites through which CRP binds and activates the classical C pathway, and suggest that these residues represent significant regions for C1q CLR binding reactions generally. To our knowledge, this represents the first delineation of sites on C1q through which binding and activation of the classical C pathway can occur.

Identification of a novel cell binding site of periostin involved in tumour growth

2011 ◽  
Vol 47 (14) ◽  
pp. 2221-2229 ◽  
Author(s):  
Paola Orecchia ◽  
Romana Conte ◽  
Enrica Balza ◽  
Patrizia Castellani ◽  
Laura Borsi ◽  
...  
Keyword(s):  
Binding Site ◽  
Tumour Growth ◽  
Cell Binding

Immunotoxins up to the present day

1989 ◽  
Vol 9 (2) ◽  
pp. 139-156 ◽  
Author(s):  
Francis A. Drobniewski
Keyword(s):  
Clinical Studies ◽  
Polyclonal Antibodies ◽  
Cell Binding ◽  
Ricin A Chain ◽  
Future Role ◽  
A Chain ◽  
Ricin A

Immunotoxins consist of monoclonal or polyclonal antibodies conjugated to bacterial or plant toxins. The toxins used are typically of the A-B type in which a toxic A chain is coupled to a B chain responsible for cell binding and facilitation of A chain entry into the cytosol. Two broad strategies have been followed: coupling intact toxins, or A chains alone, to antibodies. This review examines current progress in in vitro and in vivo research, including recent clinical studies, concentrating principally on ricin or ricin A chain conjugates. The future role of conjugates using membrane-acting toxins, immunolysins, is also discussed.

Sign in / Sign up

Export Citation Format

Share Document