Reinhard Klinger

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Signalling via seven transmembrane helix receptors can lead to a massive increase in cellular PtdIns(3,4,5)P3, which is critical for the induction of various cell responses and is likely to be produced by a trimeric G-protein-sensitive phosphoinositide 3-kinase (PI3Kgamma). We show here that PI3Kgamma is a bifunctional lipid kinase and protein kinase, and(More)
Inwardly rectifying potassium channels require binding of phosphatidylinositol-4,5-bisphosphate (PIP2) for channel activity. Three independent sites (aa 175-206, aa 207-246, aa 324-365) were located in the C-terminal domain of Kir2.1 channels by assaying the binding of overlapping fragments to PIP2 containing liposomes. Mutations in the first site, which(More)
Retinoic acid provokes growth inhibition and differentiation of the human leukemic cell line U937 to macrophage-like cells. We report that treatment of U937 cells with all-trans retinoic acid (ATRA), but not the phorbol ester 12-O-tetradecanoylphorbol-13-acetate, results in an increased gene expression of the phosphoinositide 3-kinase (PI3K) species(More)
Phosphoinositide 3-kinase gamma is a multifunctional enzyme with lipid and protein kinase activities that also acts as a scaffold protein in many diverse signalling processes. The enzyme contains five different domains, but their individual contributions to membrane binding are not fully understood. Here, using in vitro liposome binding assays of individual(More)
The activation of P2-receptors has a wide range of diverse effects in many tissues. Here we show that extracellular ATP stimulates lipogenesis in adipocytes derived from the epididymal fat pads of male Wistar rats. The lipogenic effect of ATP is not susceptible to treatment of adipocytes with adenosine deaminase or an adenosine receptor antagonist.(More)
Activation and inhibition of Ca2+-ATPase of calmodulin-depleted human erythrocyte membranes by oleic acid and a variety of other fatty acids have been measured. Low concentrations of oleic acid stimulate the enzyme activity, both in the presence and in the absence of calmodulin. Concomitantly, the affinity of the membrane bound enzyme to calmodulin(More)
Epidermal growth factor (EGF) stimulates phosphatidylinositol PtdIns) hydrolysis in many cell types by effecting the specific interaction between the EGF receptor and phospholipase C gamma. Several studies have suggested that PtdIns 4-kinase activity can also be regulated by EGF, but the mechanism of this stimulation was unclear. We report here that EGF(More)
Ca2+-ATPase was isolated from plasma membranes of Ehrlich ascites mammary carcinoma cells by means of calmodulin affinity chromatography. The purification procedure included removal of endogenous calmodulin from a Triton X-100 solubilizate of the membranes by DEAE ion-exchange chromatography as an essential step. With respect to its molecular mass,(More)
Phosphoinositide 3-kinases (PI 3-kinases) have critical roles in diverse cellular signaling processes and in protein trafficking. In contrast to the class I PI 3-kinases alpha, beta, and delta which bind via src homology 2 (SH2) domains of adaptor proteins to tyrosine kinase receptors, the mechanism of recruitment of the PI 3-kinase gamma to membranes is(More)