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Glycoprotein Ib

Platelet glycoprotein Ib (GPIb) is a heterodimeric transmembrane protein consisting of a disulfide-linked 140 kD alpha chain and 22 kD beta chain. It is part of the GPIb-V-IX system that constitutes the receptor for von Willebrand factor (VWF), and mediates platelet adhesion in the arterial circulation. GPIb alpha chain provides the VWF binding site, and GPIb beta contributes to surface expression of the receptor and participates in transmembrane signaling through phosphorylation of its intracellular domain. Mutations in the GPIb beta subunit have been associated with Bernard-Soulier syndrome, velocardiofacial syndrome and giant platelet disorder. The 206 amino acid precursor of GPIb beta is synthesized from a 1.0 kb mRNA expressed in plateletes and megakaryocytes. A 411 amino acid protein arising from a longer, unspliced transcript in endothelial cells has been described; however, the authenticity of this product has been questioned. Yet another less abundant GPIb beta mRNA species of 3.5 kb, expressed in nonhematopoietic tissues such as endothelium, brain and heart, was shown to result from inefficient usage of a non-consensus polyA signal in the neighboring upstream gene (SEPT5, septin 5). In the absence of polyadenylation from its own imperfect site, the SEPT5 gene produces read-through transcripts that use the consensus polyA signal of this gene. [provided by RefSeq, Dec 2010] (from NCBI)
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Top mentioned proteins: CD45, Gp, von Willebrand factor, Cho, ACID
Papers on GPIbbeta
Novel mutation in the glycoprotein Ibβ in a patient with Bernard-Soulier syndrome: possibility of distant parental consanguinity.
Muwakkit et al., Beirut, Lebanon. In Blood Coagul Fibrinolysis, 2012
A 14-month-old boy with Bernard-Soulier syndrome was found to be homozygous for a nonsense mutation (c.423C > A) in the glycoprotein Ib-beta.
Quaternary organization of GPIb-IX complex and insights into Bernard-Soulier syndrome revealed by the structures of GPIbβ and a GPIbβ/GPIX chimera.
Emsley et al., Nottingham, United Kingdom. In Blood, 2011
GPIbbeta missense mutations from Bernard-Soulier syndrome were examined for changes to GPIb-IX complex surface expression. Mutations A108P and P74R were found to maintain normal secretion/folding of GPIbbeta(E) but were unable to support GPIX surface expression
Delineating the roles of the GPIIb/IIIa and GP-Ib-IX-V platelet receptors in mediating platelet adhesion to adsorbed fibrinogen and albumin.
Latour et al., Cleveland, United States. In Biomaterials, 2011
GPIIb/IIIa is the primary receptor set involved in platelet adhesion to adsorbed fibrinogen and serum albumin irrespective of their degree of adsorption-induced unfolding, while the GPIb-IX-V receptor complex plays an insignificant role.
Molecular basis of Bernard-Soulier syndrome in 27 patients from India.
Srivastava et al., Vellore, India. In J Thromb Haemost, 2011
Report glycoprotein Ib/IX complex mutations found in Bernard-Soulier syndrome in Indian patients.
Platelet glycoprotein Ib beta/IX mediates glycoprotein Ib alpha localization to membrane lipid domain critical for von Willebrand factor interaction at high shear.
Peng et al., Shanghai, China. In J Biol Chem, 2011
GP Ibbeta/GP IX mediates the disulfide-linked GP Ibalpha localization to the GEMs, which is critical for vWf interaction at high shear
A central role of GPIb-IX in the procoagulant function of platelets that is independent of the 45-kDa GPIbalpha N-terminal extracellular domain.
Lanza et al., Strasbourg, France. In Blood, 2010
In GPIbbeta(-/-) mice, thrombin generation was profoundly decreased in tissue factor- or collagen-related peptide (CRP)-activated platelet-rich plasma and in washed platelets supplemented with normal plasma or with FVa, FXa, and prothrombin.
The platelet glycoprotein GPIbbeta intracellular domain participates in von Willebrand factor induced-filopodia formation independently of the Ser 166 phosphorylation site.
Lanza et al., Strasbourg, France. In J Thromb Haemost, 2010
OBJECTIVES/METHODS: To evaluate the GPIbalpha and GPIbbeta intracellular domains contribution to this signaling, we generated Chinese hamster ovary (CHO) cells expressing a GPIb-IX complex with mutant forms of the two subunits and we measured their ability to extend filopodia upon adhesion on a VWF matrix.
A GPIb-IX-V complex signaling environment.
Gardiner, Melbourne, Australia. In J Thromb Haemost, 2010
See also David T, Strassel C, Eckly A, Cazenave J-P, Gachet C, Lanza F. The platelet glycoprotein GPIbbeta intracellular domain participates in von Willebrand factor induced-filopodia formation independently of the Ser 166 phosphorylation site.
[Establishment of Chinese hamster ovary cell line expressing recombinant GPIb-IX complex].
Dai et al., Beijing, China. In Zhongguo Shi Yan Xue Ye Xue Za Zhi, 2009
The plasmids were extracted from E.coli expressing wild-type or deletion mutant GPIbalpha and were identified by digestion with EcoR I. Three plasmids containing GPIbalpha, GPIbbeta, and GPIX genes were co-transfected into CHO cells, and then the expression of GPIb-IX complex was detected by immune coprecipitation, Western blot and flow cytometry.
Binding of platelet glycoprotein Ibbeta through the convex surface of leucine-rich repeats domain of glycoprotein IX.
Li et al., Houston, United States. In J Thromb Haemost, 2009
putative convex surface of the LRR domain in GPIX is sufficient, in the context of full-length subunit, to mediate its association with GPIbbeta
Identification of five novel 14-3-3 isoforms interacting with the GPIb-IX complex in platelets.
Lanza et al., Strasbourg, France. In J Thromb Haemost, 2009
Pull-down experiments indicated that all six 14-3-3 isoforms present in platelets bind to GPIbbeta.
A novel homozygous 8-base pair deletion mutation in the glycoprotein Ibalpha gene in a patient with Bernard-Soulier syndrome.
Uchiyama et al., Niigata, Japan. In Blood Coagul Fibrinolysis, 2009
By immunoblotting, GPIbalpha, GPIbbeta and GPIX were not detected in the platelet lysates.
Intrinsic impaired proplatelet formation and microtubule coil assembly of megakaryocytes in a mouse model of Bernard-Soulier syndrome.
Lanza et al., Strasbourg, France. In Haematologica, 2009
DESIGN AND METHODS: To explore the underlying mechanisms of the disease, megakaryopoiesis was studied in a mouse model deficient in GPIbbeta.
Bernard-Soulier syndrome: novel nonsense mutation in GPIbbeta gene affecting GPIb-IX complex expression.
Gargouri et al., Sfax, Tunisia. In Ann Hematol, 2009
novel Ser 23 Stop mutation in GPIbbeta is responsible of BSS in the studied family and hampers the complex to form on the platelets surface.
Juxtamembrane basic residues in glycoprotein Ibbeta cytoplasmic domain are required for assembly and surface expression of glycoprotein Ib-IX complex.
Li et al., Houston, United States. In Febs Lett, 2008
Using transfected Chinese hamster ovary cells as the model system, we demonstrate that juxtamembrane residues 149-154 in the cytoplasmic domain of the GPIbbeta subunit is required for assembly and surface expression of the GPIb-IX complex.
Role of calmodulin in platelet receptor function.
Andrews et al., Australia. In Curr Med Chem Cardiovasc Hematol Agents, 2005
Recent evidence suggests the cytosolic regulatory protein, calmodulin, plays a central role in regulating GPVI or GPIb-IX-V: first, calmodulin directly binds to conserved, juxtamembrane motifs within cytoplasmic domains of both GPVI and GPIb-IX-V (GPIbbeta and GPV subunits) on resting platelets, interactions that dissociate upon platelet activation; second, an intact calmodulin-binding site within GPVI in transfected cells is required for CaCa2+ signaling, but not for GPVI-dependent pathways involving Src family kinases or co-associated FcRgamma-chain; and third, calmodulin regulates metalloproteinase-dependent ectodomain shedding of GPVI and GPV from human platelets.
Signalling through the platelet glycoprotein Ib-V-IX complex.
Torti et al., Pavia, Italy. In Cell Signal, 2004
The glycoprotein Ib-V-IX is one of the major adhesive receptors expressed on the surface of circulating platelets.
Genetic abnormalities of Bernard-Soulier syndrome.
Saito et al., In Int J Hematol, 2002
structure-activity relationship of mutations found in Bernard-Soulier syndrome
The platelet glycoprotein Ib-V-IX system: regulation of gene expression.
Bastian et al., Seattle, United States. In Stem Cells, 1995
Recent studies of GPIb beta transcriptional regulation suggest that an aberrant polyadenylation signal, located in the 3' end of the gene immediately upstream of the GPIb beta gene, allows in vitro expression of a rare extended fusion transcript encoding both the upstream protein and GPIb beta.
Bernard-Soulier syndrome.
Castaldi et al., In Baillieres Clin Haematol, 1989
Limited proteolytic cleavage of the complex, in particular the GP Ib alpha-chain, has allowed immunological and functional characterization of three distinct domains; a 45 kDa segment at the N-terminal end of the alpha-chain of GP Ib, which contains binding sites for von Willebrand factor and thrombin, a 90 kDa highly glycosylated region of GP Ib alpha and a membrane-associated region consisting of the remnant of GP Ib alpha disulphide-linked to GP Ib beta and non-covalently-complexed with GP IX.
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