Martin Pfaff

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Rapid modulation of ligand binding affinity ("activation") is a central property of the integrin cell adhesion receptors. Using a screen for suppressors of integrin activation, we identified the small GTP-binding protein, H-Ras, and its effector kinase, Raf-1, as negative regulators of integrin activation. H-Ras inhibited the activation of integrins with(More)
Integrin cytoplasmic domains connect these receptors to the cytoskeleton. Furthermore, integrin-cytoskeletal interactions involve ligand binding (occupancy) to the integrin extracellular domain and clustering of the integrin. To construct mimics of the cytoplasmic face of an occupied and clustered integrin, we fused the cytoplasmic domains of integrin beta(More)
The alpha4 integrins are indispensable for embryogenesis, haematopoiesis and immune responses, possibly because alpha4 regulates cellular functions differently from other integrins through its cytoplasmic tail. We used novel mimics of the alpha4 tail to identify molecules that could account for alpha4-specific signalling. Here we report that the alpha4(More)
In Rous sarcoma virus (RSV)-transformed baby hamster kidney (BHK) cells, invadopodia can self-organize into rings and belts, similarly to podosome distribution during osteoclast differentiation. The composition of individual invadopodia is spatiotemporally regulated and depends on invadopodia localization along the ring section: the actin core assembly(More)
Integrin cell-adhesion receptors mediate interactions between cells and the extracellular matrix. Dynamic regulation of integrin adhesive function is termed 'activation' or 'inside-out' signalling. Activation is key to integrin function in processes as diverse as cell migration, the organization of the extracellular matrix and platelet aggregation.(More)
Glanzmann thrombasthenia, an inherited bleeding disorder, can be caused by a defect or deficiency in platelet integrin alphaIIb beta3 (GPIIb-IIIa). Studies of thrombasthenia variants have facilitated identification of sites involved in the functions of alphaIIb beta3 and other integrins. Such sites include those that bind ligand and those that participate(More)
Cultured cells develop discrete sites of contact with the extracellular matrix, in which clustered transmembrane proteins, particularly of the integrin family of adhesion receptors, link extracellular matrix proteins to the actin cytoskeleton within the cell (Hynes, 1992). Focal adhesion plaques represent the most ubiquitous and well known of these(More)
We showed previously that the calcium-dependent protease, calpain, cleaves the cytoplasmic domain of the integrin beta3 subunit. To investigate whether susceptibility to calpain is a common feature of all integrin beta subunits, and to map calpain cleavage sites in different integrin beta tails, we treated recombinant cytoplasmic domains of integrin beta1A,(More)
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