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Dive into the research topics where Reinhard Klinger is active.

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Featured researches published by Reinhard Klinger.


FEBS Letters | 2001

Multiple PIP2 binding sites in Kir2.1 inwardly rectifying potassium channels

Malle Soom; Roland Schönherr; Yoshihiro Kubo; Cornelia Kirsch; Reinhard Klinger; Stefan H. Heinemann

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 abolished channel activity, reduced PIP2 binding of this fragment but not of the complete C‐terminus. Point mutations in the third site also reduced both, channel activity and PIP2 binding of this segment. The relevance of the third PIP2 binding site provides a basis for the understanding of constitutively active Kir2 channels.


Cell Calcium | 1980

Effect of calmodulin, Ca2+ and Mg2+ on the (Ca2+ + Mg2+)-ATPase of erythrocyte membranes

Reinhard Klinger; Reinhard Wetzker; Inga Fleischer; Horst Frunder

Abstract Calmodulin-depleted isotonic erythrocyte ghosts contain 200 ng residual calmodulin/mg protein which is not removed by extensive washings at pCa 2+ > 7. Specific activity and Ca 2+ -affinity of the (Ca 2+ + Mg 2+ )ATPase increase at increasing calmodulin, with K 0.5 Ca of 0.38 μM at calmodulin concentrations corresponding to that in erythrocytes. High Ca 2+ concentrations inhibit the enzyme. Specific activity and Ca 2+ -affinity of the enzyme decrease at increasing Mg 2+ concentrations. The Ca 2+ − Mg 2+ antagonism is likewise observed at inhibitory Ca 2+ concentrations.


Chemistry and Physics of Lipids | 1999

Phase separation in phosphatidylinositol/phosphatidylcholine mixed monolayers.

C. DeWolf; S. Leporatti; Cornelia Kirsch; Reinhard Klinger; Gerald Brezesinski

Abstract Phosphatidylinositol is a minor component of lipid membranes yet plays a major role in cellular functions. To investigate whether PI forms domains in such a system, pure and mixed monolayers of distearoylphosphatidylcholine (DSPC) and PI have been compared using surface-pressure isotherms, grazing incidence X-ray diffraction (GIXD), Brewster angle microscopy (BAM) and scanning force microscopy (SFM). The mixed (up to 20 mol% PI) monolayer isotherms exhibited a plateau region corresponding to the collapse pressure of PI. The phase separation of the mixed monolayers into a DSPC condensed phase and a PI fluid phase was confirmed by BAM and SFM measurements. DSPC forms a condensed monolayer with centred rectangular structure and tilt towards nearest neighbours (NN) while PI formed a fluid monolayer with no lateral structure at all pressures investigated. Mixed DSPC/PI monolayers containing 20 mol% PI also exhibited a centred rectangular lattice with NN tilt. At surface pressures below the collapse of the fluid, PI phase, the addition of 20 mol% PI has very little effect on the structure of the condensed phase indicating that the phases almost completely demixed.


Archives of Dermatological Research | 1989

Immunhistochemical localization of calmodulin in normal and psoriatic epidermis

Uwe Wollina; Reinhard Klinger; Reinhard Wetzker; Reissmann R; B. Knopf

Calmodulin (CAM) is a major Ca2+-binding intracellular protein of eukaryotic cells. As well as having other functions, it has been related to proliferation, cell cycle, differentiation, and spatial arrangement of intermediate filaments (for overview see [2]). CaM gained particular attention in psoriasis research with publication of the first report on raised activity in psoriatic plaques, by van de Kerkhof and van Erp in 1983 [1, 3, 7 9 , 11]. Nevertheless, no information is available about the intraepidermal distribution of this protein in psoriatic skin. As far as we know, there is only one recent report of immunohistochemical CaM detection on paraffin sections of normal human skin, suggesting a homogeneous distribution in all living cell layers [5]. Therefore, using histochemical techniques, we investigated epidermal CaM in normal and psoriatic skin. Skin biopsy specimens were obtained from healthy volunteers, and lesional and nonlesional psoriatic skin from patients after local analgesia. The tissues were snapfrozen in liquid nitrogen and processed to unfixed frozen sections of 4-1am thickness. Potyclonal anti-CaM was raised in rabbits, as previously described [10]. The working dilution was 1 : 100 in phosphate-buffered saline (PBS), pH 7.4, supplemented with 0.2% bovine serum albumin and 0.5 ml Tween 20 per liter. Tissue sections were treated with PBS-Tween 20 containing 5% goat serum for 20 min at room temperature and washed twice. Anti-CaM was added


Biochemie und Physiologie der Pflanzen | 1990

Photophysiology of Turion Germination in Spirodela polyrhiza (L. ) SCHLEIDEN. Iv. Importance of Calcium and Calmodulin

Klaus-J. Appenroth; Reinhard Klinger; Reinhard Wetzker; Helmut Augsten

Summary Light-grown as well as dark-grown (etiolated) turions of Spirodela polyrhiza are positively photoblastic. The phytochrome-mediated germination response requires supply with exogenous calcium (Ca 2+ ). Threshold value is 1.3 ± 0.3 µM Ca 2+ , half-maximal response is mediated by 16 ±2 µM Ca 2+ . Ca 2+ may be replaced in part by Sr 2+ , but not by Mg 2+ . Furthermore, the addition of the Ca 2+ -antagonists La 3+ and Co 2+ causes a complete inhibition of germination. Delayed addition of La 3+ up to 72 h after the red light pulse results in a decreased, but still significant inhibition. Germination is also inhibited by the Ca 2+ -channel blocker verapamil. On the other hand, stimulation of germination is observed without red light pulses if the Ca 2+ -ionophore A 23187 is applied for 24 h. Complete inhibition of germination is caused by the calmodulin inhibitors chlorpromazine and trifluoperazine, and, besides, calmodulin was detected in the turions. Consequently, Ca 2+ as well as calmodulin are involved in the phytochrome-mediated germination response of turions.


Cell Calcium | 1981

Transformation of (Ca2+ + Mg2+)ATPase of calmodulin-depleted erythrocyte membranes into a high Ca2+-affinity form by Ca2+

Reinhard Klinger; Reinhard Wetzker; Inga Fleischer; Horst Frunder

Abstract Specific activity and Ca2+-affinity of (Ca2++Mg2+)ATPase of calmodulin-depleted ghosts progressively increase during preincubation with 0.1–2 mM Ca2+. Concomitantly, the increment in ATPase activity caused by calmodulin and the binding of calmodulin to ghosts decrease. The effects of calcium ions are abolished by the addition of calmodulin. ATP protects the enzyme from a Ca2+-dependent decrease of the maximum activity but does not seem to influence the Ca2+-dependent transformation of the low Ca2+-affinity enzyme into a high Ca2+-affinity form.


Biophysical Journal | 2009

Adsorption of GST-PI3Kγ at the Air-Buffer Interface and at Substrate and Nonsubstrate Phospholipid Monolayers

Antje Hermelink; Cornelia Kirsch; Reinhard Klinger; Gerald Reiter; Gerald Brezesinski

The recruitment of phosphoinositide 3-kinase gamma (PI3Kgamma) to the cell membrane is a crucial requirement for the initiation of inflammation cascades by second-messenger production. In addition to identifying other regulation pathways, it has been found that PI3Kgamma is able to bind phospholipids directly. In this study, the adsorption behavior of glutathione S-transferase (GST)-PI3Kgamma to nonsubstrate model phospholipids, as well as to commercially available substrate inositol phospholipids (phosphoinositides), was investigated by use of infrared reflection-absorption spectroscopy (IRRAS). The nonsubstrate phospholipid monolayers also yielded important information about structural requirements for protein adsorption. The enzyme did not interact with condensed zwitterionic or anionic monolayers; however, it could penetrate into uncompressed fluid monolayers. Compression to values above its equilibrium pressure led to a squeezing out and desorption of the protein. Protein affinity for the monolayer surface increased considerably when the lipid had an anionic headgroup and contained an arachidonoyl fatty acyl chain in sn-2 position. Similar results on a much higher level were observed with substrate phosphoinositides. No structural response of GST-PI3Kgamma to lipid interaction was detected by IRRAS. On the other hand, protein adsorption caused a condensing effect in phosphoinositide monolayers. In addition, the protein reduced the charge density at the interface probably by shifting the pK values of the phosphate groups attached to the inositol headgroups. Because of their strongly polar headgroups, an interaction of the inositides with the water molecules of the subphase can be expected. This interaction is disturbed by protein adsorption, causing the ionization state of the phosphates to change.


Archives of Dermatological Research | 1990

Topical interferon-alpha in psoriasis increases epidermal calmodulin activity.

Uwe Wollina; B. Knopf; Reinhard Klinger

Evidence is accumulating that interferons (IFNs) are involved in psoriasis pathogenesis [8]. Both the antiproliferative and immunomodulatory activities that IFNs exert may also be useful in psoriasis therapy [7-10]. IFNalpha was shown to provide antiproliferative activity on cultured human keratinocytes [10]. Since the antiproliferative effects of different antipsoriatic drugs have been connected with their calmodulin (CAM) antagonism in vitro [1], it was our aim to investigate calmodulin activity and IFN-alpha. Five patients with stable plaque-like psoriasis and no history of antipsoriatic treatment during the previous 2 weeks participated in the study after giving informed consent: four men and one woman, aged 3 5 7 5 years (mean _+ SD, 50 + 16 years). Three lesions located on the upper legs, with a duration of less 4 weeks, and that were compareable in size, localization, and clinical score for scaling, erythema, and infiltration (score 0, no symptoms; 1, slight; 2, moderate; 3, strong)were selected for topical IFN-alpha therapy. IFN-alpha was kindly donated by the Central Institute of Microbiology and Experimental Therapy of the Academy of Sciences of the GDR, Jena. The recombinant IFN-alphal was produced in E. coli with a purity above 99%. For topical use a solution containing 1.2 x 10 v IU IFN-alpha~ in 30 m M citrate/NaOH (pH 5.1) supplemented with 10% (v/v) Gelafusal was employed. In part (a) of the experiment, one lesion per patient was treated with a single application of IFN. Punch biopsy specimens were taken after 12 h and 48 h. In part (b) of the experiment the second lesion of each patient was treated once daily with IFN for 3 5 days and a punch biopsy specimen was taken at the end of treatment. In part (c) of the experiment, the third lesion of each patient was treated once daily with the IFN-free solution


Cell Calcium | 1984

Relation between Ca2+-ATPase and endogenous calmodulin of human erythrocyte membranes.

Reinhard Klinger; Reinhard Wetzker; I. Wenz; Dinjus U; Reissmann R; Horst Frunder

Short incubation of erythrocyte membranes with oleic acid releases Ca2+-independently bound endogenous calmodulin together with a minor fraction of membrane-associated proteins without destruction of the membranes. The released endogenous calmodulin is similar if not identical to cytosolic calmodulin reversibly bound to ghosts in a Ca2+-dependent manner. The release of endogenous calmodulin proceeds without affecting the activity of Ca2+-ATPase when ghosts are incubated with oleic acid in the presence of Ca2+ plus ATP and thereafter freed from oleic acid by washings with serum albumin. Kinetic parameters of Ca2+-ATPase of ghosts with and without endogenous calmodulin are identical as are amounts of exogenous calmodulin bound to these ghosts. Thus, endogenous calmodulin does not function as an essential part of Ca2+-ATPase.


Protein Journal | 2010

Phosphoinositide 3-kinase γ has Multiple Phospholipid Binding Sites

Carsten Schmidt; Margret Schilli-Westermann; Reinhard Klinger; Cornelia Kirsch

Phosphoinositide 3-kinase γ 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 domains and deletion constructs of human phosphoinositide 3-kinase γ, we show that each domain is capable of binding anionic phospholipids to varying degrees, depending on the charge of the anionic substrate. Moreover, with the exception of the C2-domain, deletion of any single protein domain results in a complete loss of kinase activity toward both lipids and proteins.

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J. Justin Hsuan

University College London

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