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Körschen HG, Yildiz Y, Raju DN, Schonauer S, Bönigk W, Jansen V, Kremmer E, Kaupp UB, Wachten D. The non-lysosomal β-glucosidase GBA2 is a non-integral membrane-associated protein at the endoplasmic reticulum (ER) and Golgi. J Biol Chem 2012; 288:3381-93. [PMID: 23250757 DOI: 10.1074/jbc.m112.414714] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
GBA1 and GBA2 are both β-glucosidases, which cleave glucosylceramide (GlcCer) to glucose and ceramide. GlcCer is a main precursor for higher order glycosphingolipids but might also serve as intracellular messenger. Mutations in the lysosomal GBA1 underlie Gaucher disease, the most common lysosomal storage disease in humans. Knocking out the non-lysosomal GBA2 in mice results in accumulation of GlcCer outside the lysosomes in various tissues (e.g. testis and liver) and impairs sperm development and liver regeneration. However, the underlying mechanisms are not well understood. To reveal the physiological function of GBA2 and, thereby, of the non-lysosomal GlcCer pool, it is important to characterize the localization of GBA2 and its activity in different tissues. Thus, we generated GBA2-specific antibodies and developed an assay that discriminates between GBA1 and GBA2 without the use of detergent. We show that GBA2 is not, as previously thought, an integral membrane protein but rather a cytosolic protein that tightly associates with cellular membranes. The interaction with the membrane, in particular with phospholipids, is important for its activity. GBA2 is localized at the ER and Golgi, which puts GBA2 in a key position for a lysosome-independent route of GlcCer-dependent signaling. Furthermore, our results suggest that GBA2 might affect the phenotype of Gaucher disease, because GBA2 activity is reduced in Gba1 knock-out fibroblasts and fibroblasts from a Gaucher patient. Our results provide the basis to understand the mechanism for GBA2 function in vivo and might help to unravel the role of GBA2 during pathogenesis of Gaucher disease.
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Affiliation(s)
- Heinz G Körschen
- Department of Molecular Sensory Systems, Center of Advanced European Studies and Research, Ludwig-Erhard-Allee 2, 53175 Bonn, Germany
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Schulte U, Müller CS, Fakler B. Ion channels and their molecular environments – Glimpses and insights from functional proteomics. Semin Cell Dev Biol 2011; 22:132-44. [DOI: 10.1016/j.semcdb.2010.09.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Revised: 09/29/2010] [Accepted: 09/30/2010] [Indexed: 01/09/2023]
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Walerczyk M, Fabczak H, Fabczak S. Detection and localization of a putative cyclic-GMP-activated channel protein in the protozoan ciliate Stentor coeruleus. PROTOPLASMA 2006; 227:139-46. [PMID: 16736256 DOI: 10.1007/s00709-005-0143-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2005] [Accepted: 06/22/2005] [Indexed: 05/09/2023]
Abstract
Immunoblotting and immunocytochemical assays were employed to identify and localize a channel protein activated by cyclic GMP (cGMP) in the protozoan ciliate Stentor coeruleus. Analysis of whole-cell homogenate with antibodies raised against the alpha-subunit of the cGMP-activated channel protein from bovine rod outer segments and against cGMP revealed four major protein bands with molecular masses of 40 kDa, 63 kDa, and over 120 kDa, which bound cGMP. However, only a cGMP-binding protein of 63 kDa, corresponding to the alpha-subunit of the cGMP-activated ion channel protein from bovine rod outer segments, was found in the ciliate cortex fraction. The functional cGMP-activated channel protein was also shown to be present in the cortex fraction of S. coeruleus by patch-clamp measurements of artificial liposomes. Incorporation of the cortex fraction into liposomes resulted in the appearance of ion channel activity related to cGMP. The reconstituted protein channels were strongly inhibited by l-cis-diltiazem, a known potent blocker of many types of cyclic-nucleotide-activated channels. The results presented here are the first demonstration of the existence and localization of a putative cGMP-activated channel protein in the ciliate S. coeruleus. Cyclic-nucleotide-activated channel proteins are nonspecific cation channels which mediate the receptor potentials in photoreceptor cells and in cells of the olfactory epithelium. On the basis of these data, we suggest that the 63 kDa protein identified in Stentor coeruleus is also a cGMP-activated ion channel and that it may be involved as an effector in the photosensory transduction pathway leading to the motile photophobic response in this ciliate protist.
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Affiliation(s)
- M Walerczyk
- Department of Cell Biology, Nencki Institute of Experimental Biology, Polish Academy of Sciences, Warsaw, Poland
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Abstract
Cyclic nucleotide-gated (CNG) channels are nonselective cation channels first identified in retinal photoreceptors and olfactory sensory neurons (OSNs). They are opened by the direct binding of cyclic nucleotides, cAMP and cGMP. Although their activity shows very little voltage dependence, CNG channels belong to the superfamily of voltage-gated ion channels. Like their cousins the voltage-gated K+ channels, CNG channels form heterotetrameric complexes consisting of two or three different types of subunits. Six different genes encoding CNG channels, four A subunits (A1 to A4) and two B subunits (B1 and B3), give rise to three different channels in rod and cone photoreceptors and in OSNs. Important functional features of these channels, i.e., ligand sensitivity and selectivity, ion permeation, and gating, are determined by the subunit composition of the respective channel complex. The function of CNG channels has been firmly established in retinal photoreceptors and in OSNs. Studies on their presence in other sensory and nonsensory cells have produced mixed results, and their purported roles in neuronal pathfinding or synaptic plasticity are not as well understood as their role in sensory neurons. Similarly, the function of invertebrate homologs found in Caenorhabditis elegans, Drosophila, and Limulus is largely unknown, except for two subunits of C. elegans that play a role in chemosensation. CNG channels are nonselective cation channels that do not discriminate well between alkali ions and even pass divalent cations, in particular Ca2+. Ca2+ entry through CNG channels is important for both excitation and adaptation of sensory cells. CNG channel activity is modulated by Ca2+/calmodulin and by phosphorylation. Other factors may also be involved in channel regulation. Mutations in CNG channel genes give rise to retinal degeneration and color blindness. In particular, mutations in the A and B subunits of the CNG channel expressed in human cones cause various forms of complete and incomplete achromatopsia.
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Affiliation(s)
- U Benjamin Kaupp
- Institut für Biologische Informationsverarbeitung, Forschungszentrum Jülich, Jülich, Germany.
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The Complex of cGMP-Gated Channel and Na+/ Ca2+K+Exchanger in Rod Photoreceptors. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2002. [DOI: 10.1007/978-1-4615-0121-3_15] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
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6
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Hill K, Hemmler R, Kovermann P, Calenberg M, Kreimer G, Wagner R. A Ca(2+)- and voltage-modulated flagellar ion channel is a component of the mechanoshock response in the unicellular green alga Spermatozopsis similis. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1466:187-204. [PMID: 10825442 DOI: 10.1016/s0005-2736(00)00200-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
In flagellate green algae, behavioral responses to photo- and mechanoshock are induced by different external stimuli within 10-15 ms. In the accompanying changes in flagella beat, Ca(2+) has important regulatory roles. Although the axonemal Ca(2+) responsive elements are well characterized, analyses of flagellar channels involved in Ca(2+) signalling as well as other ion channels at the single-channel level were not yet conducted in green algae. To gain a further understanding of these important signaling elements in movement responses, intact flagella of Spermatozopsis similis were isolated and characterized and the solubilized flagellar membrane proteins were reconstituted into liposomes. We observed three types of channel activity, two of which were weakly anion and cation-selective and in the high-conductance regime typical for porin-like solute channels. The dominating channel activity was a voltage dependent, rectifying, low conductance (Lambda=80 pS in 50 mM KCl) cation-selective channel modulated by, and highly permeable to, Ca(2+) ions (SFC1: Spermatozopsis flagellar cation channel 1). Depolarizations necessary to activate SFC1 probably only occur in vivo during avoidance reactions of this alga. Ca(2+)-activation of SFC1 points to a direct link to Ca(2+)-mediated signaling pathway(s) in the flagella. Both the response to mechanoshock and SFC1 activity were inhibited by Gd(3+) and Ba(2+), thus supporting our assumption that SFC1 represents a major flagellar ion channel involved in this green algal avoidance reaction.
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Affiliation(s)
- K Hill
- Universität Osnabrück, Fachbereich Biologie/Chemie, Germany
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7
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Molday RS, Warren R, Kim TS. Purification and biochemical analysis of cGMP-gated channel and Na+/Ca(2+)-K+ exchanger of rod photoreceptors. Methods Enzymol 2000; 315:831-47. [PMID: 10736744 DOI: 10.1016/s0076-6879(00)15885-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Affiliation(s)
- R S Molday
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, Canada
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Affiliation(s)
- J Ahn
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, Canada
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Schwarzer A, Schauf H, Bauer PJ. Binding of the cGMP-gated channel to the Na/Ca-K exchanger in rod photoreceptors. J Biol Chem 2000; 275:13448-54. [PMID: 10788457 DOI: 10.1074/jbc.275.18.13448] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The intracellular Ca(2+) concentration in rod outer segments of vertebrate photoreceptors is controlled by Ca(2+) influx through cGMP-gated channels and by Ca(2+) efflux driven by Na/Ca-K exchangers. Previously, we suggested that channel and exchanger are associated (Bauer, P. J., and Drechsler, M. (1992) J. Physiol. (Lond. ) 451, 109-131). This suggestion has been thoroughly examined using a variety of biochemical approaches. First, we took advantage of the fact that cGMP-gated channels bind calmodulin (CaM). Using CaM affinity chromatographic purification of the channel in 10 mm CHAPS, a significant fraction of exchanger was co-eluted with the channel indicating a binding affinity between channel and exchanger. Binding of channel and exchanger was examined more directly by cross-linking of proteins in the rod outer segment membranes. Activation of the channel with cyclic 8-bromo-GMP lead to exposure of a cysteine, which allowed cross-linking of the channel to the exchanger with the thiol-specific reagent dl-1,4-bismaleimido-2,3-butanediol. Cleavage of the cross-links and electrophoretic analysis indicated that a cross-link between the alpha-subunit of the channel and the exchanger formed. Furthermore, a cross-link between two adjacent alpha-subunits of the channel was found, suggesting that the alpha-subunits of the native channel are dimerized. Further support for an interaction between alpha-subunit and exchanger was obtained by in vitro experiments. Specific binding of the exchanger to the alpha-subunit but not to the beta-subunit of the channel was observed in Western blots of purified channel incubated with purified exchanger. This study suggests that two exchanger molecules bind to one cGMP-gated channel and, more specifically, that binding of exchanger molecules occurs at the alpha-subunits, which in the native channel are dimerized. The implications of these findings regarding the possibility of local Ca(2+) signaling in vertebrate photoreceptors will be discussed.
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Affiliation(s)
- A Schwarzer
- Institute for Biological Information Processing, Research Center Juelich, D-52425 Juelich, Germany
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Molday RS, Molday LL. Purification, characterization, and reconstitution of cyclic nucleotide-gated channels. Methods Enzymol 1999; 294:246-60. [PMID: 9916231 DOI: 10.1016/s0076-6879(99)94015-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Affiliation(s)
- R S Molday
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, Canada
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11
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Ardell MD, Aragon I, Oliveira L, Porche GE, Burke E, Pittler SJ. The beta subunit of human rod photoreceptor cGMP-gated cation channel is generated from a complex transcription unit. FEBS Lett 1996; 389:213-8. [PMID: 8766832 DOI: 10.1016/0014-5793(96)00588-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Human and bovine rod photoreceptor cGMP-gated cation channel consists of two subunits: alpha (63 kDa) and beta (240 kDa). The human beta subunit was shown to consist partly of sequence encoded by the cDNA clone hRCNC2b. Here we present the complete sequence of the human beta subunit and demonstrate that the previously reported human GAR1 gene encoding a glutamate-rich protein (hGARP) encodes its N-terminal portion. Using PCR, RNA blot and genomic DNA analysis, we provide evidence that the beta subunit is produced from a complex locus on chromosome 16 which is also capable of generating independent transcripts corresponding to GAR1 and the C-terminal two-thirds of the beta subunit. The results indicate that the beta subunit of the cGMP-gated cation channel is produced from an unusual locus consisting of more than one transcription unit.
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Affiliation(s)
- M D Ardell
- Department of Biochemistry, University of South Alabama College of Medicine, Mobile, 36688-0002, USA
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12
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Huppertz B. Evidence for a cGMP gated cation channel in photoreceptor cell membranes of Sepia officinalis. FEBS Lett 1995; 364:189-92. [PMID: 7538472 DOI: 10.1016/0014-5793(95)00390-u] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
It is assumed that cyclic nucleotides are involved in signal transduction of invertebrate photoreceptors. In this study, membranes of photoreceptor cells from freshly caught cuttlefish were isolated, and the membrane proteins were reconstituted into proteoliposomes. With the dye Neutral red it was possible to measure cyclic nucleotide induced Na+ fluxes into the liposomes. cGMP and cAMP concentrations for half maximal activation of Na+ fluxes are 77 microM and 224 microM, respectively, with Hill coefficients of 2.0 for cGMP and 2.4 for cAMP. These fluxes may demonstrate the presence of at least one cyclic nucleotide gated cation channel in the membranes of the photoreceptor cells of the invertebrate Sepia officinalis.
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Affiliation(s)
- B Huppertz
- Institut für Biologie II, RWTH Aachen, Germany
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13
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Takuma K, Matsuda T, Hashimoto H, Asano S, Baba A. Cultured rat astrocytes possess Na(+)-Ca2+ exchanger. Glia 1994; 12:336-42. [PMID: 7890336 DOI: 10.1002/glia.440120410] [Citation(s) in RCA: 82] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Na(+)-Ca2+ exchange activity in its reverse mode was demonstrated in cultured rat astrocytes. Combination of ouabain (1 mM) and monensin (20 microM) caused a marked increase in 45Ca2+ uptake in astrocytes. 45Ca2+ uptake was also stimulated by lowering the external Na+ concentration. Ouabain plus monensin-stimulated 45Ca2+ uptake was blocked by 3,4-dichlorobenzamil (IC50, 16 microM), an inhibitor of Na(+)-Ca2+ exchanger, but not by nifedipine (0.1 microM). The stimulated-45Ca2+ uptake was observed even in K(+)-free medium, and external K+ at 5-10 mM caused a 2.2-fold increase in the uptake. Microspectrofluorimetry using the Ca(2+)-sensitive dye fura-2 showed that ouabain plus monensin increased intracellular Ca2+ concentration in single astrocytes. The Ca2+ signal was dependent on external Ca2+ (EC50, 1.4 mM), and blocked by 20 microM 3,4-dichlorobenzamil, but not by Ca2+ channel blockers (Cd2+, 20 microM; Ni2+, 100 microM). Antiserum of cardiac Na(+)-Ca2+ exchanger recognized 160 and 120-135 kDa proteins on SDS-polyacrylamide gel electrophoresis of astrocyte homogenate. Northern blot analysis revealed the presence of mRNA for the exchanger protein in astrocytes. These findings indicate that Na(+)-Ca2+ exchanger which is modulated by K+ is present in cultured rat astrocytes.
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Affiliation(s)
- K Takuma
- Department of Pharmacology, Faculty of Pharmaceutical Sciences, Osaka University, Japan
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14
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Huppertz B, Bauer PJ. Na(+)-Ca2+,K+ exchange in bovine retinal rod outer segments: quantitative characterization of normal and reversed mode. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1189:119-26. [PMID: 8292615 DOI: 10.1016/0005-2736(94)90056-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Ca2+ homeostasis of bovine retinal rod outer segments is maintained through Na(+)-Ca2+,K+ exchangers and cGMP-gated channels in the plasma membrane. It has recently been demonstrated that both proteins are associated. This novel finding allowed us to investigate quantitatively normal and reversed mode Na(+)-Ca2+,K+ exchange in rod outer segment membrane vesicles and reconstituted proteoliposomes both containing exchangers in rightside-out and inside-out orientations. Addition of Na+ activated both normal and reversed mode exchange; if, however, initially Ca2+ from vesicles containing inside-out oriented exchangers has been released by activation of the associated channels, only normal mode exchange was observed upon addition of Na+. Using this approach, the fractions of vesicles containing rightside-out and inside-out oriented exchangers were about similar in these vesicle preparations. Normal and reversed mode exchange had similar Na+ concentrations of about 70 mM for half maximal activation (in the presence of 115 mM K+) and cooperativity parameters, nHill, of about 2.0. Furthermore, both modes were electrogenic, and showed only little Na(+)-Ca2+,K+ exchange in the absence of K+. The two modes of exchange differed, however, in the maximal exchange rate, the normal mode being about twice as fast as the reversed mode.
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Affiliation(s)
- B Huppertz
- Institut für Biologische Informationsverarbeitung, Forschungszentrum Jülich, Germany
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15
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Gruber HJ, Schindler H. External surface and lamellarity of lipid vesicles: a practice-oriented set of assay methods. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1189:212-24. [PMID: 8292627 DOI: 10.1016/0005-2736(94)90068-x] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Three methods are presented for the determination of external surface of large lipid vesicles of different lamellarity with 2% absolute accuracy. These methods (referred to as EPR, NBD and TNBS assays) use different marker lipids which provide signals (electron paramagnetic resonance, fluorescence of N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl) residues, and UV absorption increase of 2,4,6-trinitrobenzenesulfonic acid after reaction with aminolipids, respectively). The signals change upon addition of different membrane-impermeant reagents due to reaction with marker lipids at the external vesicle surface. They were applied to the same vesicle samples, including unilamellar and multilamellar vesicles, both at two different lipid compositions. External surface data matched for the three assays within 2%, but only after appropriate redesign or adaptation of so far published procedures. Main improvements related to slow influx of reagents (TNBS and NBD assays) or to redistribution of marker lipids (EPR assay), obscuring determination of outer vesicle surface from fast reaction between reagent and readily accessible marker lipids. Furthermore, suitable strategies were found to obtain accurate 100% values (reaction of all marker lipids present), required to relate external vesicle surface to total surface. This included corrections for light scattering (NBD assay) and for turbidity (TNBS assay). These three methods appear to close a gap in the methodology to determine external surface of vesicles for typical practical needs. In particular, the reliability range of the NBD assay could be extended to marker lipid densities as low as 1 marker lipid per 3000 lipids.
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Affiliation(s)
- H J Gruber
- Institut for Biophysics, J. Kepler University, Linz, Austria
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16
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Koch KW. Calcium as modulator of phototransduction in vertebrate photoreceptor cells. Rev Physiol Biochem Pharmacol 1993; 125:149-92. [PMID: 7984873 DOI: 10.1007/bfb0030910] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- K W Koch
- Institut für Biologische Informationsverarbeitung, Forschungszentrum Jülich, Germany
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17
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Simultaneous Purification and Characterization of the cGMP-Gated Cation Channel and the Na+/Ca2+,K+-Exchanger. ACTA ACUST UNITED AC 1993. [DOI: 10.1016/b978-0-12-185279-5.50025-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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18
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Schulenburg P, Schwarz M, Wagner R. Inhibition of chloroplast ATPase by the K+ channel blocker alpha-dendrotoxin. EUROPEAN JOURNAL OF BIOCHEMISTRY 1992; 210:257-67. [PMID: 1446675 DOI: 10.1111/j.1432-1033.1992.tb17416.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Possible structural and functional similarities between the channel part, CF0, of chloroplast ATPase (CF0CF1) and ion channels permeable to monovalent cations were investigated using high-affinity toxins mainly targeted against voltage-sensitive K+ channels. In particular, the effect of the K(+)-channel blocker alpha-dendrotoxin and the crude scorpion venom of Leiurus quinquestriatus hebraeus (LQ venom) on ATP synthesis in thylakoid membranes and in CF0CF1-containing liposomes was characterised. Alpha-dendrotoxin (K(i) approximately 5.05 microM) and the LQ venom (K(i) approximately 1.55 micrograms/ml) specifically inhibited ATP synthesis in thylakoid membranes and in CF0CF1-containing liposomes. Our results show that alpha-dendrotoxin and peptides of the LQ venom with an apparent molecular mass of about 4.0 kDa, probably isoforms of charybdotoxin, specifically bind to CF0CF1. This binding was reversible and induced a high leak conductance for H+ through CF0. The Ca(2+)-dependent ATPase activity of the isolated soluble part of CF0CF1 (CF1) was completely inhibited by 1 microM alpha-dendrotoxin, while the crude LQ venom, at concentrations up to 10 micrograms/ml, had no affect on ATPase activity. The concentration dependence of the inhibition by alpha-dendrotoxin indicates that approximately 2 mol alpha-dendrotoxin bind/mol CF0CF1 and 1 mol alpha-dendrotoxin/mol CF1. Known inhibitors of H(+)-flow-through CF0 acted in the presence of alpha-dendrotoxin synergistically. Dicyclohexylcarbodiimide and venturicidin, in contrast to their known effect of blocking H(+)-flow-through CF0, increased the leak conductance through CF0 in the presence of alpha-dendrotoxin drastically. This uncoupling effect indicates that their normal mode of blocking is a secondary effect. Binding of the inhibitors to their respective sites apparently does not affect the proton pathway in CF0, but induces a conformation which closes the channel part for H+. Protein sequence comparison between the known binding site of charybdotoxin in the shaker K+ channel from Drosophila [MacKinnon, R. & Heginbotham, L. (1990) Neuron 5, 767-771] and the choroplast ATPase showed that subunit III reveals a significant similarity (64%) in parts of its sequence (Gln28-Leu53) to the helix 5 and helix 6 (S5-S6) linker region (Ala413-Cys462; the charybdotoxin-binding site) of the shaker K+ channel. According to secondary-structure predictions, the homologous sequences in subunit III and the shaker K+ channel represent putative hydrophilic loops connecting two transmembrane alpha-helices. Apparently the shaker K+ channel and subunit III share significant topological features in these hydrophilic loops which may be part of the respective channel entrance.
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Affiliation(s)
- P Schulenburg
- Biophysik, Universität Osnabrück, FB Biologie/Chemie, Federal Republic of Germany
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Pittler S, Lee A, Altherr M, Howard T, Seldin M, Hurwitz R, Wasmuth J, Baehr W. Primary structure and chromosomal localization of human and mouse rod photoreceptor cGMP-gated cation channel. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)42689-0] [Citation(s) in RCA: 88] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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20
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Buchanan S, Michel H, Gerwert K. Light-induced charge separation in Rhodopseudomonas viridis reaction centers monitored by Fourier-transform infrared difference spectroscopy: the quinone vibrations. Biochemistry 1992; 31:1314-22. [PMID: 1736990 DOI: 10.1021/bi00120a006] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Static FTIR light-induced difference spectra have been recorded for reaction centers from Rhodopseudomonas viridis in the following charge-separated states: P+QA(-)-PQA, P+QB(-)-PQB, I(-)-I, I-QA(-)-IQA, and I-QA(2-)-IQA. A comparison of the I(-)-I difference spectra with the I-QA(-)-IQA difference spectra reveals new bands which can be assigned to QA- vibrations; these vibrations are also observed in the P+QA(-)-PQA and P+QB(-)-PQB difference spectra. Through an analysis of all of the static difference spectra, the electron-transfer pathway can be monitored in the infrared from the primary donor, P, to the secondary acceptor, QB, via the intermediate acceptor, I, and the primary acceptor, QA. The difference spectra are dominated by absorbance changes of prosthetic groups, with very few identifiable contributions from amino acids and little overall structural change in the protein backbone, involving only one or two residues for the various charge-separated states. Oxidation of the primary donor in the reaction center shows the characteristic absorbance changes of the 9-keto and 10-ester carbonyl groups observed upon oxidation of bacteriochlorophyll b in a non-hydrogen-bonded environment [Ballschmiter, K. H., & Katz, J. J. (1969) J. Am. Chem. Soc. 91, 2661-2677]. Reduction of the quinones in the reaction center yields absorbance changes of the carbonyls observed during reduction of quinones in a hydrogen-bonded environment [Bauscher, M., Nabedryk, E., Bagley, K., Breton, J., & Mäntele, W. (1990) FEBS Lett. 261, 191-195].(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- S Buchanan
- Max-Planck-Institut für Biophysik, Frankfurt, Germany
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Wohlfart P, Haase W, Molday RS, Cook NJ. Antibodies against synthetic peptides used to determine the topology and site of glycosylation of the cGMP-gated channel from bovine rod photoreceptors. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)48542-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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22
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Cyclic Nucleotide-gated Channels — A Family of Proteins Involved in Vertebrate Photoreception and Olfaction. ACTA ACUST UNITED AC 1992. [DOI: 10.1007/978-3-642-76482-0_15] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Achilles A, Friedel U, Haase W, Reiländer H, Cook NJ. Biochemical and molecular characterization of the sodium-calcium exchanger from bovine rod photoreceptors. Ann N Y Acad Sci 1991; 639:234-44. [PMID: 1785849 DOI: 10.1111/j.1749-6632.1991.tb17310.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- A Achilles
- Max-Planck-Institut für Biophysik, Abteilung für Molekulare Membranbiologie, Frankfurt am Main, Federal Republic of Germany
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24
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Molday R, Molday L, Dosé A, Clark-Lewis I, Illing M, Cook N, Eismann E, Kaupp U. The cGMP-gated channel of the rod photoreceptor cell characterization and orientation of the amino terminus. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)54724-4] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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25
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Oecking C, Weiler EW. Characterization and purification of the fusicoccin-binding complex from plasma membranes of Commelina communis. EUROPEAN JOURNAL OF BIOCHEMISTRY 1991; 199:685-9. [PMID: 1868852 DOI: 10.1111/j.1432-1033.1991.tb16171.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The fungal phytotoxin fusicoccin binds with high affinity to plasma membranes of the monocotyledonous plant, Commelina communis L. The sites bind the toxin with an apparent Kd of 5.2 nM and a pH optimum of 6.0. They occur at a level of approximately 6-8 pmol/mg plasma membrane protein. Photoaffinity labeling with the biologically active fusicoccin derivative 9'-nor-8'-(4-azido[3,5-3H]benzoyl) diaminoethylfusicoccin identified a polypeptide of 31.5 kDa on SDS/PAGE which was strongly labeled. A second 32.5-kDa band was also consistently labeled, although not to the same extent. The binding sites were solubilized in functional form and a purification scheme was developed based on affinity and ion-exchange procedures. The purified fraction contains two polypeptides of apparent molecular masses of 30.5 kDa and 31.6 kDa. A detailed molecular analysis of the fusicoccin-binding complex is now possible.
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Affiliation(s)
- C Oecking
- Lehrstuhl für Pflanzenphysiologie, Ruhr-Universität Bochum, Federal Republic of Germany
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26
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Ildefonse M, Bennett N. Single-channel study of the cGMP-dependent conductance of retinal rods from incorporation of native vesicles into planar lipid bilayers. J Membr Biol 1991; 123:133-47. [PMID: 1720176 DOI: 10.1007/bf01998084] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Unitary currents through cGMP-dependent channels of retinal rods are observed following incorporation into planar lipid bilayers of native vesicles from purified rod outer segment membranes washed free of soluble and peripheral proteins. The influence of the concentration of cGMP, inhibitors (cis-diltiazem, tetracaine and Ag+) and divalent cations (Ca2+, Mg2+, and Co2+) on the conductance and open probability of the channel is described, as well as the voltage dependence of these effects. The cGMP dependence suggests the existence of four binding sites for cGMP and reveals that sequential binding of four cGMP molecules corresponds to the opening of four discrete conductance levels. Finally, we provide conclusive evidence that activated G-protein does not directly inactivate the cGMP-dependent channels of bovine retinal rods.
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Affiliation(s)
- M Ildefonse
- Unité de Recherche Associée 520 du Centre National de la Recherche Scientifique, Centre d'Etudes Nucléaires de Grenoble, France
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27
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Caretta A, Sorbi RT, Stein PJ, Tirindelli R. Diltiazem at high concentration increases the ionic permeability of biological membranes. J Membr Biol 1991; 122:203-13. [PMID: 1717690 DOI: 10.1007/bf01871421] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The effects of diltiazem, a drug which inhibits the calcium channels in cardiac muscle as well as the light-sensitive channels in photoreceptor cells, were studied on ionic fluxes in both membrane and intact cell preparations. Diltiazem nonselectively increased the ionic permeability to both anions and cations in photoreceptor rod outer segment and synaptic membrane vesicles as well as in intact erythrocytes. Under our conditions, the estimated threshold for the diltiazem effect varied between 12.5 and 200 microM. In each case the concentration dependence exhibited the sigmoidal shape characteristic of positive cooperativity. The effect of diltiazem on ionic fluxes from phospholipid vesicles were strongly influenced by phospholipid composition and membrane charge. By contrast, diltiazem inhibited the efflux of 86Rb from photoreceptor cells of intact aspartate-isolated retina, an effect opposite to that of diltiazem on ionic permeabilities in photoreceptor membrane vesicle preparations. These data raise serious doubts on the specificity of diltiazem as a calcium channel blocker or as a cGMP channel blocker when used at concentrations higher than 10 microM.
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Affiliation(s)
- A Caretta
- Istituto di Fisiologia Umana, Università di Parma, Italy
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28
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Devenny JJ, Clack JW. Calcium release from rod outer segments: evidence for a cGMP-sensitive calcium binding protein. Biochem Biophys Res Commun 1991; 176:70-8. [PMID: 1850272 DOI: 10.1016/0006-291x(91)90891-a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Numerous studies investigating the cGMP-gated cation conductance in rod disk membranes have purported to measure efflux of Ca2+ entrapped in rod disk membrane vesicles. We have utilized sonication and osmotic shock as additional tests for sensitivity of cGMP- and A23187-induced Ca2+ release to elimination of the transvesicular Ca2+ gradient. We find that 1) Treatment with sonication or osmotic shock in low Ca2+ medium does not release Ca2+ from either native cGMP/Ca2(+)-loaded vesicles or solubilized, reconstituted "Ca2(+)-loaded" vesicles, 2) 70-100% of the cGMP-induced "flux" and 90-100% of the A23187-induced Ca2+ "flux" is insensitive to elimination of the Ca2+ gradient by sonication or osmotic shock in low Ca2+ medium, and 3) total amount of releasable Ca2+ is related to membrane surface area rather than vesicle entrapment volume. We conclude that 1) A23187 disrupts binding of Ca2+ to proteins and phospholipids as well as releasing entrapped Ca2+ and 2) a large fraction of the cGMP-induced release observed in rod disk vesicles is due to release of bound Ca2+.
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Affiliation(s)
- J J Devenny
- Department of Ophthalmology and Visual Science, Yale University School of Medicine, New Haven, CT 06510
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29
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Kaupp UB. The cyclic nucleotide-gated channels of vertebrate photoreceptors and olfactory epithelium. Trends Neurosci 1991; 14:150-7. [PMID: 1710853 DOI: 10.1016/0166-2236(91)90087-b] [Citation(s) in RCA: 169] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Cation channels that are directly gated by guanosine 3', 5'-cyclic monophosphate (cGMP) control the flow of ions across the surface membrane of vertebrate rod and cone photoreceptor cells. A similar channel, gated by adenosine 3',5'-cyclic monophosphate (cAMP), exists in vertebrate olfactory sensory neurons. The channel polypeptide of rod photoreceptors has been identified and the amino acid sequence of the channel polypeptide in rod and olfactory cells has been determined by cloning cDNA. Although the cyclic nucleotide-gated channels functionally belong to the class of ligand-gated channels, they share some structural features with voltage-gated channels.
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Affiliation(s)
- U B Kaupp
- Institut für Biologische Informations-Verarbeitung, Forschungszentrum Jülich, FRG
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30
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Friedel U, Wolbring G, Wohlfart P, Cook NJ. The sodium-calcium exchanger of bovine rod photoreceptors: K(+)-dependence of the purified and reconstituted protein. BIOCHIMICA ET BIOPHYSICA ACTA 1991; 1061:247-52. [PMID: 1998696 DOI: 10.1016/0005-2736(91)90290-o] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The K(+)-dependence of the rod photoreceptor sodium-calcium exchanger was investigated using the Ca2(+)-sensitive dye arsenazo III after reconstitution of the purified protein into proteoliposomes. The uptake of Ca2+ by Na(+)-loaded liposomes was found to be greatly enhanced by the presence of external K+ (EC50 approximately 1 mM) in a Michaelis-Menten manner, suggesting that one K+ ion is involved in the transport of one Ca2+ ion. We also found a minimal degree of Ca2+ uptake in the total absence of K+. Other alkali cations, notably Rb+ and, to a lesser extent, Cs+, were also able to stimulate Na(+)-Ca2+ exchange. We also investigated the K(+)-dependence of the photoreceptor Na(+)-Ca2+ exchanger by determining the effects of electrochemical K+ gradients on the Na(+)-activated Ca2+ efflux from proteoliposomes. We found that, under conditions of membrane voltage clamp with FCCP, inwardly directed electrochemical K+ gradients (i.e., K0+ greater than Ki+) inhibited, whereas an outwardly directed electrochemical K+ gradient (i.e., Ki+ greater than K0+) enhanced, Na(+)-dependent Ca2+ efflux, consistent with the notion that K+ is cotransported in the same direction as Ca2+. The investigation of the reconstituted exchanger at physiological (i.e. Ki+ = 110 mM, K0+ = 2.5 mM) potassium concentrations revealed that the Na(+)-dependence of Ca2(+)-efflux was highly cooperative (n = 3.01 from Hill plots), indicating that at least three, but possibly four, Na+ ions are exchanged for one Ca2+ ion. Under these conditions the reconstituted exchanger showed a Km for Na+ of 26.1 mM, and a turnover number of 115 Ca2+.s-1 per exchanger molecule. Our results with the purified and reconstituted sodium-calcium exchanger from rod photoreceptors are therefore consistent with previous reports (Cervetto, L., Lagnado, L., Perry, R.J., Robinson, D.W. and McNaughton, P.A. (1989) Nature 337, 740-743; Schnetkamp, P.P.M., Basu, D.K. and Szerencsei, R.T. (1989) Am. J. Physiol. 257, C153-C157) that the sodium-calcium exchanger of rod photoreceptors cotransports K+ under physiological conditions with a stoichiometry of 4 Na+:1 Ca2+, 1K+.
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Affiliation(s)
- U Friedel
- Max-Planck-Institut für Biophysik, Abteilung für Molekulare Membranbiologie, Frankfurt am Main, F.R.G
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31
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Krapivinsky GB, Filatova EA, Filatov GN, Jainazarov AB, Mantzygin YuA, Fesenko EE. Antiidiotypic antibodies interacting with cGMP-dependent channels of frog retinal rod outer segments. JOURNAL OF RECEPTOR RESEARCH 1991; 11:757-72. [PMID: 1717686 DOI: 10.3109/10799899109064678] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Antiidiotypic approach was used to obtain antibodies interacting with cGMP-binding site of the cGMP-activated channel of the photoreceptor cell. Monoclonal anti-BrcGMP antibodies having characteristics of binding of agonist and its analogs close to those for a natural receptor have been obtained. These antibodies were used to raise polyclonal antiidiotypic antibodies capable of interacting with a natural cGMP-receptor. Application of immunoglobulins, isolated from antiidiotypic serum, to inside-out fragments of the rod plasma membrane led to an irreversible increase of the conductance of cGMP-dependent channels.
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Affiliation(s)
- G B Krapivinsky
- Laboratory of Biophysics of Reception, USSR Academy of Sciences, Moscow Region
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32
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The cGMP-gated cation channel of bovine rod photoreceptor cells is associated with a 240-kDa protein exhibiting immunochemical cross-reactivity with spectrin. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(17)44807-1] [Citation(s) in RCA: 102] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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33
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Wohlfart P, Vienhues R, Cook NJ. Spectrophotometric determination of photoreceptor cGMP-gated channel Mg2(+)-fluxes using dichlorophosphonazo III. BIOCHIMICA ET BIOPHYSICA ACTA 1990; 1022:283-90. [PMID: 1690570 DOI: 10.1016/0005-2736(90)90275-s] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We have characterised the spectroscopic properties of the metallochromic dye dichlorophosphonazo III and describe its use for the determination of changes of Mg2+ concentration in the micromolar range. Using a previously described reconstitution procedure, we incorporated the cGMP-gated channel from bovine rod photoreceptors into magnesium-containing liposomes and used the dye to monitor cGMP-activated Mg2(+)-efflux. The Km and cooperativity of the cGMP-dependence were identical regardless of whether Mg2+ or Ca2+ was the transported ion, however, the vmax for Ca2+ was more than 2-fold higher than that for Mg2+. We thereby determined a channel selectivity (Ca2+:Mg2+) of 1.0:0.44 in the presence of symmetrical (30 mM) K+. We also describe conditions where Mg2+ or Ca2+ effluxes can be selectively monitored in the presence of each other. This allowed the demonstration that magnesium ions can flow through the cGMP-gated channel even in the presence of an identically directed calcium gradient. Together these results indicate that magnesium ions may enter the photoreceptor rod outer segment cytosol through the cGMP-gated channel under dark conditions, thereby alluding to the existence of an as yet unknown Mg2(+)-extrusion mechanism, distinct from the Na+/Ca2(+)-exchanger, in these cells.
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Affiliation(s)
- P Wohlfart
- Max-Planck-Institut für Biophysik, Abteilung Molekulare Membranbiologie, Frankfurt/Main, F.R.G
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34
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Reid DM, Friedel U, Molday RS, Cook NJ. Identification of the sodium-calcium exchanger as the major ricin-binding glycoprotein of bovine rod outer segments and its localization to the plasma membrane. Biochemistry 1990; 29:1601-7. [PMID: 2334719 DOI: 10.1021/bi00458a035] [Citation(s) in RCA: 61] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
After neuraminidase treatment the Na+/Ca2+ exchanger of bovine rod outer segments was found to specifically bind Ricinus communis agglutinin. SDS gel electrophoresis and Western blotting of ricin-binding proteins purified from rod outer segment membranes by lectin affinity chromatography revealed the existence of two major polypeptides of Mr 215K and 103K, the former of which was found to specifically react with PMe 1B3, a monoclonal antibody specific for the 230-kDa non-neuraminidase-treated Na+/Ca2+ exchanger. Reconstitution of the ricin affinity-purified exchanger into calcium-containing liposomes revealed that neuraminidase treatment had no significant effect on the kinetics of Na+/Ca2+ exchange activation by sodium. We further investigated the density of the Na+/Ca2+ exchanger in disk and plasma membrane preparations using Western blotting, radioimmunoassays, immunoelectron microscopy, and reconstitution procedures. The results indicate that the Na+/Ca2+ exchanger is localized in the rod photoreceptor plasma membrane and is absent or present in extremely low concentrations in disk membranes, as we have previously shown to be the case for the cGMP-gated cation channel. Previous reports describing the existence of Na+/Ca2+ exchange activity in rod outer segment disk membrane preparations may be due to the fusion of plasma membrane components and/or the presence of contaminating plasma membrane vesicles.
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Affiliation(s)
- D M Reid
- Department of Biochemistry, University of British Columbia, Vancouver, Canada
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35
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36
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Investigation of Quinone Reduction in Rhodopseudomonas viridis by FTIR Difference Spectroscopy and X-Ray Diffraction Analysis. ACTA ACUST UNITED AC 1990. [DOI: 10.1007/978-3-642-61297-8_8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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37
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Kaupp UB, Niidome T, Tanabe T, Terada S, Bönigk W, Stühmer W, Cook NJ, Kangawa K, Matsuo H, Hirose T. Primary structure and functional expression from complementary DNA of the rod photoreceptor cyclic GMP-gated channel. Nature 1989; 342:762-6. [PMID: 2481236 DOI: 10.1038/342762a0] [Citation(s) in RCA: 550] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The complete amino-acid sequence of the cyclic GMP-gated channel from bovine retinal rod photoreceptors, deduced by cloning and sequencing its complementary DNA, shows that the protein contains several putative transmembrane segments, followed by a region that is similar to the cyclic GMP-binding domains of cyclic GMP-dependent protein kinase. Expression of the complementary DNA produces cyclic GMP-gated channel activity in Xenopus oocytes.
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Affiliation(s)
- U B Kaupp
- Department of Medical Chemistry, Kyoto University Faculty of Medicine, Japan
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38
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Wohlfart P, Müller H, Cook NJ. Lectin Binding and Enzymatic Deglycosylation of the cGMP-Gated Channel from Bovine Rod Photoreceptors. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(19)30026-2] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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39
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40
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Calcium channel activation and inactivation inParamecium biochemically measured by cyclic GMP production. J Membr Biol 1989. [DOI: 10.1007/bf01870283] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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41
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Interaction of the γ-subunit of retinal rod outer segment phosphodiesterase with transducin. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)80117-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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42
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Feyerabend M, Weiler EW. Photoaffinity labeling and partial purification of the putative plant receptor for the fungal wilt-inducing toxin, fusicoccin. PLANTA 1989; 178:282-290. [PMID: 24212894 DOI: 10.1007/bf00391855] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/1988] [Accepted: 01/13/1989] [Indexed: 06/02/2023]
Abstract
The high-affinity fusicoccin-binding protein (FCBP) was solubilized from plasma-membrane vesicles prepared from leaves of Vicia faba L. by aqueous two-phase partitioning. Conditions for the solubilization of intact FCBP-radioligand complexes were worked out. About 60-70% of the complexes can be solubilized with 50-60 mM nonanoyl-N-methylglucamide in the presence of 1 mg· ml(-1) soybean phosphatidylcholine, type IV S, and 20% (v/v) glycerol at pH 5.5. The slow dissociation of the radioligand, 9'-nor-fusicoccin-8'-alcohol-[(3)H] from the FCBP at low temperatures permits the purification of FCBP-radioligand complexes at 4-10° C by fast protein liquid chromatography on anion-exchange and gel permeation columns. The FCBP, extracted from plasma membranes with cholate and chromatographed in the presence of this detergent, gave an apparent molecular mass (Mr) of 80±20 kDa on gel permeation columns under the conditions used. By comparison of the elution profiles of the fraction most enriched in FCBP-radioligand complexes with polypeptide patterns obtained on sodium dodecyl sulfate-polyacrylamide gels, a polypeptide with an Mr of approx. 34kDa co-separated with the radioactivity profile. A second, faint band of approx. 31 kDa was sometimes also observed co-electrophoresing. Photoaffinity labeling of plasma-membrane vesicles with the new compound 9'-nor-8'[(3,5-[(3)H]-4-azidobenzoy)ethylenediamine]-fusicoccin ([(3)H]ABE-FC) and subsequent separation by sodium dodecyl sulfate-polyacrylamide gel electrophoresis labeled a single band with an Mr of 35±1 kDa. Labeling in this band was strongly reduced when the membranes were incubated with [(3)H]ABE-FC in the presence of 0.1-1 μM fusicoccin. From our data, we conclude (i) that the 34-35-kDa polypeptide represents the FCBP and (ii) that in detergent extracts of plasma membranes this polypeptide is probably present as a di- or trimeric structure.
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Affiliation(s)
- M Feyerabend
- Arbeitsgruppe Pflanzenphysiologie, Fachbereich Biologie/Chemie, Universität Osnabrück, Postfach 4469, D-4500, Osnabrück, Federal Republic of Germany
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43
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44
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Cook NJ, Molday LL, Reid D, Kaupp UB, Molday RS. The cGMP-gated Channel of Bovine Rod Photoreceptors Is Localized Exclusively in the Plasma Membrane. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)83530-x] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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45
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Cook NJ, Kaupp UB. Solubilization, purification, and reconstitution of the sodium-calcium exchanger from bovine retinal rod outer segments. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)37968-7] [Citation(s) in RCA: 56] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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46
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Becker U, Nuske J, Stieve H. Phototransduction in the microvillar visual cell of Limulus: Electrophysiology and biochemistry. ACTA ACUST UNITED AC 1988. [DOI: 10.1016/0278-4327(88)90027-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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47
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Morrison DF, Rider MA, Takemoto DJ. Modulation of retinal transducin and phosphodiesterase activities by synthetic peptides of the phosphodiesterase gamma-subunit. FEBS Lett 1987; 222:266-70. [PMID: 2820805 DOI: 10.1016/0014-5793(87)80383-6] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Synthetic peptides corresponding to various regions of the light-activated guanosine 3',5'-cyclic monophosphate phosphodiesterase (PDE) gamma-subunit (PDE gamma) from bovine retinal rod outer segments were synthesized and tested for their ability to inhibit PDE activity, and GTPase activity of transducin. One of these peptides, corresponding to PDE gamma residues 31-45, inhibited PDE activity and GTPase activity in a dose-dependent manner. The GTPase activity was inhibited by PDE gamma-3 non-competitively. This region of the PDE gamma subunit may be involved in the direct interaction of transducin and PDE alpha beta with PDE gamma.
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Affiliation(s)
- D F Morrison
- Department of Biochemistry, Kansas State University, Manhattan 66506
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48
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Koch KW, Cook NJ, Kaupp UB. The cGMP-dependent channel of vertebrate rod photoreceptors exists in two forms of different cGMP sensitivity and pharmacological behavior. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)47810-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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49
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Montal M. Reconstitution of channel proteins from excitable cells in planar lipid bilayer membranes. J Membr Biol 1987; 98:101-15. [PMID: 2444708 DOI: 10.1007/bf01872123] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- M Montal
- Department of Neurosciences, Roche Institute of Molecular Biology, Nutley, New Jersey 07110
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50
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