scholarly journals Human platelet membrane receptor for bovine von Willebrand factor (platelet aggregating factor): An integral membrane glycoprotein

1979 ◽  
Vol 76 (3) ◽  
pp. 1069-1073 ◽  
Author(s):  
H. A. Cooper ◽  
K. J. Clemetson ◽  
E. F. Luscher
Keyword(s):  
Von Willebrand Factor ◽  
Human Platelet ◽  
Membrane Receptor ◽  
Platelet Membrane ◽  
Membrane Glycoprotein ◽  
Platelet Membrane Receptor ◽  
Von Willebrand ◽  
Willebrand Factor

Glycoprotein Ib Has a Partial Role in Platelet-von Willebrand Factor Collagen Interaction

1988 ◽  
Vol 60 (02) ◽  
pp. 182-187 ◽  
Author(s):  
Morio Aihara ◽  
Ken Tamura ◽  
Ryuko Kawarada ◽  
Keizou Okawa ◽  
Yutaka Yoshida
Keyword(s):  
Platelet Aggregation ◽  
Von Willebrand Factor ◽  
Ricinus Communis ◽  
Protein S ◽  
Platelet Membrane ◽  
Membrane Glycoprotein ◽  
Normal Plasma ◽  
Ricinus Communis Agglutinin ◽  
Von Willebrand ◽  
Willebrand Factor

SummaryThe adhesion of human fixed washed platelets (FWP) to collagen was decreased after treatment with Serratia marcescens protease (SP), which removed 95% of the glycocalicin from platelet membrane glycoprotein (GP) lb. However, the diminished adhesion of SP treated FWP to collagen could still be increased in the presence of purified von Willebrand factor (vWF). This ability of vWF to increase FWP adhesion to collagen is defined as collagen cofactor (CCo). The adhesion of FWP to collagen was not affected by a monoclonal antibody (MAb) to GP Ilb/IIIa (10E5), that inhibits ADP and collagen induced platelet aggregation. On the other hand, it was decreased by 50% by a MAb to GP lb (6D1), that inhibits ristocetin induced platelet aggregation. Adhesion of FWP in buffer to collagen was completely inhibited by Ricinus communis agglutinin I or concanavalin A, while Lens culinalis agglutinin and wheat germ agglutinin showed 50% inhibition. The FWP adhesion to collagen in the presence of vWF (normal plasma) was unaffected by MAbs to GP Ilb/IIIa (10E5, P2, HPL1) but was decreased to 32-38% by MAbs to GP lb (6D1, AN51, HPL11). A MAb to vWF (CLB-RAg 35), that inhibits ristocetin induced binding of vWF to platelets, decreased the CCo of normal plasma by 70%. The MAb, CLB-RAg 201, that inhibits the binding of vWF to collagen, completely inhibited the CCo of normal plasma. In conclusion, our data suggest that (1) GP lb has a partial role in FWP adhesion to collagen; (2) the binding of vWF to collagen is required for the expression of CCo; (3) CCo is partly mediated through GP lb; but (4) other platelet membrane protein(s) besides GP lb or GP Ilb/IIIa must also be involved in FWP-vWF-collagen interactions.

Ristocetin and Botrocetin Involve Two Distinct Domains of von Willebrand Factor for Binding to Platelet Membrane Glycoprotein lb

1990 ◽  
Vol 64 (02) ◽  
pp. 326-332 ◽  
Author(s):  
J P Girma ◽  
Y Takahashi ◽  
A Yoshioka ◽  
J Diaz ◽  
D Meyer
Keyword(s):  
Von Willebrand Factor ◽  
Synthetic Peptides ◽  
Competitive Inhibition ◽  
Final Concentration ◽  
Binding Domain ◽  
Platelet Membrane ◽  
Platelet Glycoprotein ◽  
Membrane Glycoprotein ◽  
Von Willebrand ◽  
Willebrand Factor

SummaryWe have evidence that ristocetin and botrocetin mediate binding of von Willebrand Factor (vWF) to platelet glycoprotein lb (GPIb) through two distinct domains on the vWF molecule. This was established by using monoclonal antibodies (MAbs) to vWF and synthetic peptides derived from the sequence of vWF. MAb 322 and MAb NMC/vW 4 both recognize native vWF as well as fragments containing the GPIb-binding domain of vWF, obtained with the following enzymes: trypsin (116 kDa), V-8 pro tease (Spill, 320 kDa) and V-8 protease plus subtilisin (33-28 kDa). Nevertheless, the lack of reciprocal displacement between the two MAbs in experiments of competitive inhibition for binding to vWF demonstrate that their respective epitopes are separate. Both MAbs inhibit 125I-vWF binding to platelet membrane GPIb and vWF-dependent platelet agglutination induced by ristocetin. However, only MAb NMC/vW4 inhibits these functions in the presence of botrocetin and when ristocetin-induced platelet agglutination is inhibited by MAb 322, botrocetin is still able to restore the agglutination. The involvement of two distinct domains of vWF for binding to GPIb in the presence of ristocetin or botrocetin was confirmed in experiments of binding of 125I-vWF to platelets using as competitor synthetic peptides corresponding to the GPIb binding domain of vWF (Cys 474 to Pro 488 and Ser 692 to Pro 708). At a final concentration of 2.5 mM both peptides inhibit more than 90% of the binding of vWF to ristocetin-treated platelets but are unable to modify this binding in the presence of botrocetin. In conclusion our data suggest that botrocetin and ristocetin involve distinct sites on vWF for binding to GPIb.

CHARACTERIZATION OF THE VON WILLEBRAND FACTOR-BINDING DOMAIN OF PLATELET MEMBRANE GLYCOPROTEIN Ib

1987 ◽  
Author(s):  
M Handa ◽  
K Titani ◽  
K Takio ◽  
Z M Ruggeri
Keyword(s):  
Von Willebrand Factor ◽  
Binding Domain ◽  
Platelet Membrane ◽  
Membrane Glycoprotein ◽  
Tryptic Fragment ◽  
Amino Terminal ◽  
Platelet Membrane Glycoprotein ◽  
Limited Digestion ◽  
Von Willebrand ◽  
Willebrand Factor

We have previously obtained immunochemical evidence that the von Willebrand factor (vWF)-binding domain of the platelet membrane glycoprotein (GP) Ib is located near the amino terminus of the a subunit (Journal of Biological Chemistry 261: 12579-12585, 1986). We have now determined the complete amino acid sequence of the 45 kDa tryptic fragment of glycocalicin that contains this domain. Purified glycocalicin was subjected to limited digestion with trypsin and the proteolytic fragments were separated by size-exclusion high-pressure liquid chromatography. Two fragments of 45 kDa and 84 kDa, respectively, were obtained under nonreducing conditions. After reduction and S-carboxymethylation, the 84 kDa fragment was unchanged, while the 45 kDa fragment yielded two new fragments, one of 35 kDa and the other of 7 kDa. This finding proves the existence of a trypsin cleavage site within a disulfide loop. Two primary sets of overlapping fragments were obtained by cleavage of the carboxymethylated protein at methionyl and lysyl bonds following treatment with cyanogen bromide and Achromobacter protease I, respectively. Additional fragments were obtained by treatment of glycocalicin with Staphylococcus aureus V8 protease and Serratia marcescens protease. Analysis of all these fragments provided data that allowed determination of the sequence of the amino terminal 299 residues of the GP Ib a-chain. This includes the 45 kDa tryptic fragment containing the vWF-binding domain. This 299-residue sequence, corresponding approximately to two thirds of the α-chain polypeptide, is largely hydrophobic and contains only two N-linked and one O-linked carbohydrate chains. A hydrophilic region exists between residues 215-299, with a cluster of ten negatively charged residues at 269-287. This area is likely to attract positively charged molecules. The hydrophilic, highly glycosylated (at Ser/Thr residues) region corresponding to the previously described "macroglycopeptide" begins at residue 292. The determined sequence of glycocalicin contains a region with seven repeats, indicative of gene duplication, and is highly homologous to human leucine-rich α2-glycoprotein.

Structure and function of the von Willebrand factor A1 domain: analysis with monoclonal antibodies reveals distinct binding sites involved in recognition of the platelet membrane glycoprotein Ib-IX-V complex and ristocetin-dependent activation

Blood ◽  
2000 ◽  
Vol 95 (1) ◽  
pp. 164-172 ◽  
Author(s):  
Mariagrazia De Luca ◽  
David A. Facey ◽  
Emmanuel J. Favaloro ◽  
Mark S. Hertzberg ◽  
James C. Whisstock ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Platelet Aggregation ◽  
Von Willebrand Factor ◽  
Platelet Membrane ◽  
Membrane Glycoprotein ◽  
Platelet Membrane Glycoprotein ◽  
And Function ◽  
A1 Domain ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract Binding of the adhesive glycoprotein, von Willebrand factor (vWf), to the platelet membrane glycoprotein (GP) Ib-IX-V complex initiates platelet adhesion and aggregation at high shear stress in hemostasis and thrombosis. In this study, the GP Ib-IX-V binding site within the vWf A1 domain was analyzed using a panel of murine monoclonal antibodies raised against a 39/34-kd vWf fragment (Leu-480/Val-481–Gly-718) encompassing the A1 domain. One antibody, 6G1, strongly inhibited ristocetin-dependent vWf binding to platelets, but had no effect on botrocetin- or jaracetin-dependent binding, or asialo-vWf–dependent platelet aggregation. The 6G1 epitope was mapped to Glu-700–Asp-709, confirming the importance of this region for modulation of vWf by ristocetin. Like ristocetin, 6G1 activated the vWf A1 domain, because it enhanced binding of the 39/34-kd fragment to platelets. In contrast, 5D2 and CR1 completely inhibited asialo-vWf–induced platelet aggregation and ristocetin-induced vWf binding to GP Ib-IX-V. However, only 5D2 blocked botrocetin- and jaracetin-induced vWf binding to platelets and binding of vWf to botrocetin- and jaracetin-coated beads. Epitopes for 5D2 and CR1 were conformationally dependent, but not congruent. Other antibodies mapped to epitopes within the A1 domain (CR2 and CR15, Leu-494–Leu-512; CR2, Phe-536–Ala-554; CR3, Arg-578–Glu-596; CR11 and CR15, Ala-564–Ser-582) were not functional, identifying regions of the vWf A1 domain not directly involved in vWf-GP Ib-IX-V interaction. The combined results provide evidence that the proline-rich sequence Glu-700–Asp-709 constitutes a regulatory site for ristocetin, and that ristocetin and botrocetin induce, at least in part, separate receptor-recognition sites on vWf. (Blood. 2000;95:164-172)

THE FUNCTIONAL DOMAIN OF PLATELET MEMBRANE GLYCOPROTEIN lb FOR VON WILLEBRAND FACTOR AND THROMBIN-BINDING

1987 ◽  
Author(s):  
M Taki ◽  
K Sato ◽  
Y Ikeda ◽  
M Yamamoto ◽  
K Watanabe
Keyword(s):  
Monoclonal Antibody ◽  
Von Willebrand Factor ◽  
Platelet Membrane ◽  
Functional Domain ◽  
Membrane Glycoprotein ◽  
Dependent Manner ◽  
Platelet Surface ◽  
Platelet Membrane Glycoprotein ◽  
Von Willebrand ◽  
Willebrand Factor

In this paper, we have examined the functional domain of platelet membrane glycoprotein lb (GPIb) by using elastase and a monoclonal antibody against GPIb which specific inhibits both von Willebrand factor (vWF) and thrombin interaction with platelets. Elastase was purified from human granulocytes by using affinity column chromatography according to the method of Okada et al.. A monoclonal antibody against platelet membrane GPIb (56-2) which inhibits both vWF and thrombin-binding to platelets was used for this study. Platelet surface glycoproteins were labelled with 3H by the method of Nurden et al.. Purified GPIb was obtained by a modification of the method of Coller et al. and labelled with 125I using chloramine-T method. Either 3H-labelled platelets or 125I-labelled GPIb was treated with elastase for various time periods. Elastase-treated l25I-GPIb was subjected to immunoaffinity chromatography using 56-2 antibody to determine the functional site of GPIb. Elastase inhibited platelet aggregation or 5-HT release by thrombin, ristocetin-induced platelet agglutination and vWF-binding to platelets in the presence of ristocetin in a dose- and time dependent manner. A fluorogram of SDS-PAGE of 3H-labelled platelets treated with elastase revealed that GPIb band was reduced gradually, and fragments with MW of 97, 70, 60, 47, 44, 37, 25 and 15 KD were released from the platelets. The 47 KD fragment was initially cleaved from the platelets, and subsequently other fragments were digested. Similar results were obtained when purified 125I-GPIb was digested by elastase. When the fragments from purified 125I-GPIb were reacted with 56-2 antibody, only three fragments with MW of 47, 44 and 25 KD were immunoisolated. The electrophoretic mobility of all these three bands was altered under reduced conditions, indicating that all these fragments contain disulfide bonds in their molecules. The 25 KD band showed a much fainter in 3H-labelling than in 125I-labelling.These results suggest that the functional domains of GPIb for both vWF and thrombin-binding may be located in a less glycosylated fragment with a MW of 25 KD on the distal portion of the GPIb molecule, which should contain at least one intramolecular disulfide bond.

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