Martin E . Hemler

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Cell-surface proteins of the tetraspanin family are small, and often hidden by a canopy of tall glycoprotein neighbours in the cell membrane. Consequently, tetraspanins have been understudied and underappreciated, despite their presence on nearly all cell and tissue types. Important new genetic evidence has now emerged, and is bolstered by new insights into(More)
This review summarizes key aspects of tetraspanin proteins, with a focus on the functional relevance and structural features of these proteins and how they are organized into a novel type of membrane microdomain. Despite the size of the tetraspanin family and their abundance and wide distribution over many cell types, most have not been studied. However,(More)
Cytokine-activated human endothelial cells express vascular cell adhesion molecule-1 (VCAM-1), which binds lymphocytes. We now identify the integrin VLA-4 as a receptor for VCAM-1 because VLA-4 surface expression on K-562 cells (following transfection of the VLA alpha 4 subunit cDNA) resulted in specific cell adhesion to VCAM-1, and anti-VLA-4 antibodies(More)
The capability of the integrin VLA-3 to function as a receptor for collagen (Coll), laminin (Lm), and fibronectin (Fn) was addressed using both whole cell adhesion assays and ligand affinity columns. Analysis of VLA-3-mediated cell adhesion was facilitated by the use of a small cell lung carcinoma line (NCI-H69), which expresses VLA-3 but few other(More)
The monoclonal antibody 9EG7 has been previously found to recognize an epitope induced by manganese on the integrin beta 1 chain (Lenter, M., Uhlig, H., Hamann, A., Jeno, P., Imhof, B., and Vestweber, D. (1993) Proc. Natl. Acad. Sci. U.S.A. 90, 9051-9055). Here we show that treatment of beta 1 integrins with manganese or soluble integrin ligands (e.g.(More)
The alpha3beta1 integrin forms complexes with other cell-surface proteins, including transmembrane-4 superfamily (TM4SF) proteins (e. g. CD9, CD53, CD63, CD81, and CD82). To identify additional cell-surface proteins associated with alpha3beta1 integrin, a monoclonal antibody selection protocol was developed. Mice were immunized with integrin(More)
Recent literature suggests that tetraspanin proteins (transmembrane 4 superfamily; TM4SF proteins) may associate with each other and with many other transmembrane proteins to form large complexes that sometimes may be found in lipid rafts. Here we show that prototype complexes of CD9 or CD81 (TM4SF proteins) with alpha(3)beta(1) (an integrin) and complexes(More)
Here we describe an association between alpha3beta1 integrin and transmembrane-4 superfamily (TM4SF) protein CD151. This association is maintained in relatively stringent detergents and thus is remarkably stable in comparison with previously reported integrin-TM4SF protein associations. Also, the association is highly specific (i.e., observed in vitro in(More)
Extracellular matrix metalloproteinase inducer (EMMPRIN; CD147) is a heavily glycosylated protein containing two immunoglobulin superfamily domains. It is enriched on the surface of tumor cells and stimulates the production of matrix metalloproteinases (MMPs) by adjacent stromal cells. Here we use CD147 transfectants and immobilized recombinant CD147-Fc(More)