Martine Billard

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By associating with specific partner molecules and with each other, the tetraspanins are thought to assemble multimolecular complexes that may be especially relevant with respect to metastasis. We have previously identified a 135-kDa molecule (CD9P-1) as a major molecular partner of CD9 in cancer cell lines. This molecule was identified, after(More)
CD9, CD63, CD81, and CD82 are glycoproteins of unknown function which belong to the tetraspan superfamily. These molecules have short cytoplasmic sequences, four transmembrane domains and two unequal extracellular regions. Here, we show that these molecules are associated with each other on cell surface and with other glycoproteins such as very late antigen(More)
Several tetraspanins bind directly to a few molecular partners to form primary complexes, which might assemble through tetraspanin-tetraspanin interactions to form a network of molecular interactions, the tetraspanin web. We have produced a monoclonal antibody directed to a 63 kDa molecule (determined under non-reducing conditions) associated with CD9. This(More)
The CD9 antigen is a cell surface glycoprotein of unknown function which belongs to the tetraspans family. We demonstrate here, by precipitation, Western blotting and co-capping experiments, that this molecule is associated with a large fraction of beta 1 integrins in two cell lines, the pre-B cell line NALM-6 and the megakaryocytic cell line HEL. In HEL(More)
The tetraspanin web refers to a network of molecular interactions involving tetraspanins and other molecules. Inside the tetraspanin web, small primary complexes containing only one tetraspanin and one specific partner molecule such as CD151/alpha3beta1 integrin and CD9/CD9P-1 (FPRP) can be observed under particular conditions. Here we demonstrate that when(More)
Several cytokines and growth factors are released by proteolytic cleavage of a membrane-anchored precursor, through the action of ADAM (a disintegrin and metalloprotease) metalloproteases. The activity of these proteases is regulated through largely unknown mechanisms. In this study we show that Ab engagement of several tetraspanins (CD9, CD81, CD82)(More)
The CD9 antigen was described originally as a 24-kDa surface protein of non-T acute lymphoblastic leukemia cells and developing B-lymphocytes. It is also strongly expressed on platelets, among other cells, where it shows the property of mediating platelet activation and aggregation upon binding with mAbs. The primary structure has been elucidated by cloning(More)
The tetraspans associate with a large number of surface molecules, including a subset of beta1 integrins and, indirectly through CD19, with the complement receptor CD21. To further characterize the tetraspan complexes we have raised and selected monoclonal antibodies (mAb) for their ability to immunoprecipitate a molecule associated with CD9. A unique mAb(More)
The CD19-CD21-CD81 complex regulates signal transduction events critical for B lymphocyte development and humoral immunity. CD81, a molecule with 4 transmembrane domains, member of the tetraspan superfamily, is engaged, together with other tetraspans such as CD9, CD53, CD63, and CD82, in multimolecular complexes containing beta1 integrins and major(More)
The tetraspanins associate with various surface molecules and with each other to build a network of molecular interactions, the tetraspanin web. The interaction of tetraspanins with each other seems to be central for the assembly of the tetraspanin web. All tetraspanins studied, CD9, CD37, CD53, CD63, CD81, CD82 and CD151, were found to incorporate(More)