Abstract
AlF4- has long been known to associate with and activate the GDP-bound alpha subunits of heterotrimeric G-proteins. Recently the small guanine nucleotide binding protein Ras has also been shown to associate with AlF4- in the presence of stoichiometric amounts of its GTPase activating protein (GAP). Here we present the isolation of a stable Ras x GDP- x AlF4- x GAP ternary complex by gel filtration. In addition, we generalise the association of AlF4- with the small GTP-binding proteins by demonstrating ternary complex formation for the Cdc42, Rap and Ran proteins in the presence of their respective GAP proteins.
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De novo expression of the class-A macrophage scavenger receptor conferring resistance to apoptosis in differentiated human THP-1 monocytic cells.
The class-A macrophage scavenger receptor (MSR) is a trimeric multifunctional protein expressed selectively in differentiated monomyeloid phagocytes which mediates uptake of chemically modified lipoproteins and bacterial products. This study investigated whether MSR plays a role in the regulation of apoptosis, a model of genetically programmed cell death. De novo expression
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Fluoroaluminates activate transducin-GDP by mimicking the gamma-phosphate of GTP in its binding site.
Fluoride activation of the cGMP cascade of vision requires the presence of aluminum, and is shown to be mediated by the binding of one A1F-4 to the GDP/GTP-binding subunit of transducin. The presence of GDP in the site is required: A1F-4 is ineffective when the site is empty or when
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The biochemistry and physiology of metallic fluoride: action, mechanism, and implications
Fluoride is a well-known G protein activator. Activation of heterotrimeric GTP-binding proteins by fluoride requires trace amounts of Al3+ or Be2+ ions. AlFx mimics a gamma-phosphate at its transition state in a Galpha protein and is therefore able to inhibit its GTPase activity. AlFx also forms complexes with small GTP-binding
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Fluoride complexes of aluminium or beryllium act on G-proteins as reversibly bound analogues of the gamma phosphate of GTP.
Fluoride activation of G proteins requires the presence of aluminium or beryllium and it has been suggested that AIF4- acts as an analogue of the gamma-phosphate of GTP in the nucleotide site. We have investigated the action of AIF4- or of BeF3- on transducin (T), the G protein of the
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Phosphatidylinositol 4,5-bisphosphate hydrolysis accompanies T cell receptor-induced apoptosis of murine thymocytes within the thymus.
Regulation of the development of thymocytes into mature T cells within the thymus is now known to involve antigen-induced deletion, by apoptosis, of potentially autoreactive thymocytes, and it can be mimicked either by stimulating the T cell receptor (TcR) complex by monoclonal antibody (mAb) or by ionophore-induced elevation of cytosolic
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