126
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Martin BR, Stein JM, Kennedy EL, Doberska CA, Metcalfe JC. Transient complexes. A new structural model for the activation of adenylate cyclase by hormone receptors (guanine nucleotides/irradiation inactivation). Biochem J 1979; 184:253-60. [PMID: 230831 PMCID: PMC1161759 DOI: 10.1042/bj1840253] [Citation(s) in RCA: 40] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
1. The irradiation-inactivation procedure was used to study changes in the state of association of the protein components of adenylate cyclase in intact rat liver plasma membranes by measurement of alterations in the target size determined from the catalytic activity of the enzyme. 2. A decrease in target size at 30 degrees C in response to p[NH]ppG (guanosine 5'-[betagamma-imido]triphosphate) or GTP was demonstrated, which we take to reflect the dissociation of a regulatory subunit. The effect of GTP is potentiated by glucagon. This effect is not observed at 0 degrees C. 3. An increase in target size was observed in response to glucagon in the absence of guanine nucleotides, which we take to reflect the association of glucagon receptor with adenylate cyclase. 4. We propose a model for the activation of adenylate cyclase by glucagon in which the binding of the hormone to its receptor causes an initial association of the receptor with the catalytic unit of the enzyme and a regulatory subunit to form a ternary complex. The subsequent activation of the adenylate cyclase results from the dissociation of the ternary complex to leave a free catalytic unit in the activated state. This dissociation requires the binding of a guanine nucleotide to the regulatory subunit. 5. The effects of variation of temperature on the activation of adenylate cyclase by glucagon and guanine nucleotides were examined and are discussed in relation to the irradiation-activation data. 6. The effectiveness of hormones, guanine nucleotides and combinations of hormone and guanine nucleotides as activators of adenylate cyclase in both rat liver and rat fat-cell plasma membranes was studied and the results are discussed in relation to the model proposed, which is also considered in relation to the observations published by other workers.
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127
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Smith GA, Hesketh TR, Plumb RW, Metcalfe JC. The exogenous lipid requirement for histamine release from rat peritoneal mast cells stimulated by concanavalin A. FEBS Lett 1979; 105:58-62. [PMID: 90622 DOI: 10.1016/0014-5793(79)80887-x] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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128
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Richards CD, Martin K, Gregory S, Keightley CA, Hesketh TR, Smith GA, Warren GB, Metcalfe JC. Degenerate perturbations of protein structure as the mechanism of anaesthetic action. Nature 1978; 276:775-9. [PMID: 723953 DOI: 10.1038/276775a0] [Citation(s) in RCA: 167] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The interaction of the n-alkanols with lipid bilayers and excitable membranes shows that there is no simple correlation between conduction block and any of the perturbations of bilayer structure currently proposed as unitary mechanisms of local anaesthetic action. We propose instead that the n-alkanols act by direct interaction with target proteins to cause perturbations which depend directly on the precise structure of the alcohol.
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129
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Bennett JP, Smith GA, Houslay MD, Hesketh TR, Metcalfe JC, Warren GB. The phospholipid headgroup specificity of an ATP-dependent calcium pump. BIOCHIMICA ET BIOPHYSICA ACTA 1978; 513:310-20. [PMID: 152650 DOI: 10.1016/0005-2736(78)90201-8] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
We have replaced the lipid associated with a purified calcium transport protein with a series of defined synthetic dioleoyl phospholipids in order to determine the effect of phospholipid headgroup structure on the ATPase activity of the protein. At 37 degrees C the zwitterionic phospholipids (dioleoyl phosphatidylcholine and dioleoyl phosphatidylethanolamine) support the highest activity, while a phospholipid with two negative charges (dioleoyl phosphatidic acid) supports an activity which is at least twenty times lower. Dioleoyl phospholipids with a single net negative charge support at intermediate ATPase activity which is not affected by the precise chemical structure of the phospholipid headgroup. The protocol used to determine the phospholipid headgroup specificity of calcium transport protein is novel because it establishes the composition of the lipid in contact with the protein without the need to isolate defined lipid-protein complexes. This allows the lipid specificity to be determined using only very small quantities of test lipids. We also determined the ability of the same phospholipids to support calcium accumulation in reconstituted membranes. Two requirements had to be met. The phospholipid had to support the ATPase activity of the pump protein and it had to form sealed vesicles as determined by electron microscopy. Since a number of phospholipids met those requirements it is clear that in vitro the lipid specificity of the calcium-accumulating system is rather broad.
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130
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Metcalfe JC, Richards CD. The effects of temperature on the local anaesthetic action of primary alcohols [proceedings]. J Physiol 1978; 281:35P-36P. [PMID: 702391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
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131
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Hesketh TR, Keightley CA, Metcalfe JC, Richards CD. Long-chain alcohols (C10-C12) can block nerve impulses [proceedings]. J Physiol 1978; 278:5P-6P. [PMID: 671336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
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132
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Hesketh TR, Smith GA, Houslay MD, Warren GB, Metcalfe JC. Is an early calcium flux necessary to stimulate lymphocytes? Nature 1977; 267:490-4. [PMID: 327331 DOI: 10.1038/267490a0] [Citation(s) in RCA: 99] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Concentrations of concanavalin A or the calcium ionophore A23187 that are optimal for the transformation of pig or mouse lymphocytes do not normally cause a measurable increase in calcium influx compared with unstimulated cells. If the cells are treated with the mitogens in conditions where a measurable increase in calcium influx occurs, no stimulation of the cells can occur while the flux is maintained. If an early influx of extracellular calcium is necessary for stimulation, then a much smaller increase in the total concentration of cellular calcium than reported previously is sufficient to allow the entry of lymphocytes into the cell cycle.
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133
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Houslay MD, Ellory JC, Smith GA, Hesketh TR, Stein JM, Warren GB, Metcalfe JC. Exchange of partners in glucagon receptor-adenylate cyclase complexes. Physical evidence for the independent, mobile receptor model. BIOCHIMICA ET BIOPHYSICA ACTA 1977; 467:208-19. [PMID: 195604 DOI: 10.1016/0005-2736(77)90197-3] [Citation(s) in RCA: 105] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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134
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Warren GB, Metcalfe JC. What is the phospholipid specificity of a reconstituted calcium pump? Biochem Soc Trans 1977; 5:517-20. [PMID: 143381 DOI: 10.1042/bst0050517a] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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135
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Hesketh TR, Smith GA, Houslay MD, McGill KA, Birdsall NJ, Metcalfe JC, Warren GB. Annular lipids determine the ATPase activity of a calcium transport protein complexed with dipalmitoyllecithin. Biochemistry 1976; 15:4145-51. [PMID: 183811 DOI: 10.1021/bi00664a002] [Citation(s) in RCA: 232] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Pure complexes of dipalmitoyllecithin (DPL, 16:0) which Ca2+, Mg2+ dependent ATPase from sarcoplasmic reticulum are unusual in retaining significant ATPase activity down to about 30 degrees C, well below the transition temperature of the pure lipid at 41 degrees C. A minimum of about 35 lipid molecules per ATPase is required to maintain maximal ATPase activity, but the complexes are progressively and irreversibly inactivated at lower lipid to protein ratios. Complexes containing more than the minimum lipid requirement show very similar temperature profiles of activity about 30 degrees C over a wide range of lipid to protein ratios, up to 1500:1. Spin-label studies indicate that, at lipid to protein ratios of less than about 30 lipids per ATPase, no DPL phase transition can be detected, but at all higher ratios, a phase transition occurs at about 41 degrees C. In all of these complexes there are breaks in the Arrhenius plots of ATPase activity at 27--32 degrees C and at 37.5--38.5 degrees C. Experiments with perturbing agents, such as cholesterol and benzyl alcohol which have well-defined effects on the DPL phase transition, indicate that these breaks in the Arrhenius plots of ATPase activity cannot be attributed to a depressed and broadened phase transition in the lipids near the protein molecules. These results are interpreted as evidence for a phospholipid annulus of at least 30 lipid molecules with interact directly with the ATPase and cannot undergo a phase transition at 41 degrees C. This structural interaction of the ATPase with the annular DPL molecules has a predominant effect in determining the form of the temperature-activity profiles. However, the perturbation of the DPL phase transition does not extend significantly beyond the annulus since a phase transition which starts at 41 degrees C can be detected as soon as extraannular lipid is present in the complexes. We suggest that it may be a general feature of membrane structure that penetrant membrane proteins interact with their immediate lipid environment so as to cause only a minimal perturbation of the lipid bilayer.
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Houslay MD, Metcalfe JC, Warren GB, Hesketh TR, Smith GA. The glucagon receptor of rat liver plasma membrane can couple to adenylate cyclase without activating it. BIOCHIMICA ET BIOPHYSICA ACTA 1976; 436:489-94. [PMID: 179598 DOI: 10.1016/0005-2736(76)90210-8] [Citation(s) in RCA: 139] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
1. Activation of adenylate cyclase in rat liver plasma membranes by fluoride or GMP-P (NH)P yielded linear Arrheniun plots. Activation by glucagon alone, or in combination with either fluoride or GMP-P(NH)P resulted in biphasic Arrhenius plots with a well-defined break at 28.5 +/- 1 degrees C. 2. The competitive glucagon antagonist, des-His-glucagon did not activate the adenylate cyclase but produced biphasic Arrhenius plots in combination with fluoride or GMP-P(NH)P. The break temperatures and activation energies were very similar to those observed with glucagon alone, or in combination with either fluoride or GMP-P(NH)P. 3. It is concluded that although des-His-glucagon is a potent antagonist of glucagon, it nevertheless causes a structural coupling between the receptor and the catalytic unit.
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137
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Houslay MD, Hesketh TR, Smith GA, Warren GB, Metcalfe JC. The lipid environment of the glucagon receptor regulates adenylate cyclase activity. BIOCHIMICA ET BIOPHYSICA ACTA 1976; 436:495-504. [PMID: 179599 DOI: 10.1016/0005-2736(76)90211-x] [Citation(s) in RCA: 112] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
1. The lipids composition of rat liver plasma membranes was substantially altered by introducing synthetic phosphatidylcholines into the membrane by the techniques of lipid substitution or lipid fusion. 40-60% of the total lipid pool in the modified membranes consisted of a synthetic phosphatidylcholine. 2. Lipid substitution, using cholate to equilibrate the lipid pools, resulted in the irreversible loss of a major part of the adenylate cyclase activity stimulated by F-, GMP-P(NH)P or glucagon. However, fusion with presonicated vesicles of the synethic phosphatidylcholines causes only small losses in adenylate cyclase activity stimulated by the same ligands. 3. The linear form of the Arrhenius plots of adenylate cyclase activity stimulated by F- or GMP-(NH)P was unaltered in all of the membrane preparations modified by substitution or fusion, with very similar activation energies to those observed with the native membrane. The activity of the enzyme therefore appears to be very insensitive to its lipid environment when stimulated by F- or gmp-p(nh)p. 4. in contrast, the break at 28.5 degrees C in the Arrhenius plot of adenylate cyclase activity stimulated by glucagon in the native membrane, was shifted upwards by dipalmitoyl phosphatidylcholine, downwards by dimyristoyl phosphatidylcholine, and was abolished by dioleoyl phosphatidylcholine. Very similar shifts in the break point were observed for stimulation by glucagon or des-His-glucagon in combination with F- or GMP-P(NH)P. The break temperatures and activation energies for adenylate cyclase activity were the same in complexes prepared with a phosphatidylcholine by fusion or substitution. 5. The breaks in the Arrhenius plots of adenylate cyclase activity are attributed to lipid phase separations which are shifted in the modified membranes according to the transition temperature of the synthetic phosphatidylcholine. Coupling the receptor to the enzyme by glucagon or des-His-glucagon renders the enzyme sensitive to the lipid environment of the receptor. Spin-label experiments support this interpretation and suggest that the lipid phase separation at 28.5 degrees C in the native membrane may only occur in one half of the bilayer.
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Lee AG, Birdsall NJ, Metcalfe JC, Warren GB, Roberts GC. A determination of the mobility gradient in lipid bilayers by 13C nuclear magnetic resonance. PROCEEDINGS OF THE ROYAL SOCIETY OF LONDON. SERIES B, BIOLOGICAL SCIENCES 1976; 193:253-74. [PMID: 6966 DOI: 10.1098/rspb.1976.0045] [Citation(s) in RCA: 41] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The spin-lattice relaxation times of individual
13
C nuclei in phospholipid bilayers have been measured by using both natural-abundance
13
C and selectively
13
C-enriched phospholipids. These relaxation times can be analysed to give values for the diffusion coefficients for motion about individual carbon-carbon bonds, and for motion about the long axis of the hydrocarbon chains in the bilayer. The assumptions involved in this analysis are examined, and the values obtained compared with those for
n
-alkanes, and with the results of studies of molecular motion in lipid bilayers by other methods. The results indicate that motion about carbon-carbon bonds in phospholipid bilayers is relatively rapid, and emphasize the fluid nature of the hydrocarbon chain region of such bilayers. This picture of the bilayer is compared with that obtained by techniques which measure time-average conformational properties of the hydrocarbon chains in the bilayer.
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139
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Warren GB, Houslay MD, Metcalfe JC, Birdsall NJ. Cholesterol is excluded from the phospholipid annulus surrounding an active calcium transport protein. Nature 1975; 255:684-7. [PMID: 124402 DOI: 10.1038/255684a0] [Citation(s) in RCA: 267] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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140
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141
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Houslay MD, Warren GB, Birdsall NJ, Metcalfe JC. Lipid phase transitions control beta-hydroxybutyrate dehydrogenase activity in defined-lipid protein complexes. FEBS Lett 1975; 51:146-51. [PMID: 1168149 DOI: 10.1016/0014-5793(75)80873-8] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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142
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Birdsall NJ, Ellar DJ, Lee AG, Metcalfe JC, Warren GB. 13C-enriched phosphatidylethanolamines from Escherichia coli. BIOCHIMICA ET BIOPHYSICA ACTA 1975; 380:344-54. [PMID: 1091295 DOI: 10.1016/0005-2760(75)90020-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Escherichia coli have been grown using [1-13C]acetate and [2-13C]acetate as the sole carbon source. The 13C NMR spectra of the whole cells and spheroplasts can be readily obtained but give limited information. The 13C NMR spectra of t-e isolated 13C-enriched phosphatidylethanolamines are assigned and analysed to give the biosynthetic pathway for acetate incorporation. This method provides a ready source of 13C-enriched phospholipids.
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143
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Warren GB, Metcalfe JC, Lee AG, Birdsall NJ. Mg2+ regulates the ATPase activity of a calcium transport protein by interacting with bound phosphatidic acid. FEBS Lett 1975; 50:261-4. [PMID: 122941 DOI: 10.1016/0014-5793(75)80503-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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144
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Warren GB, Toon PA, Birdsall NJ, Lee AG, Metcalfe JC. Reversible lipid titrations of the activity of pure adenosine triphosphatase-lipid complexes. Biochemistry 1974; 13:5501-7. [PMID: 4281664 DOI: 10.1021/bi00724a008] [Citation(s) in RCA: 241] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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145
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Lee AG, Birdsall NJ, Metcalfe JC, Toon PA, Warren GB. Clusters in lipid bilayers and the interpretation of thermal effects in biological membranes. Biochemistry 1974; 13:3699-705. [PMID: 4368511 DOI: 10.1021/bi00715a013] [Citation(s) in RCA: 215] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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146
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Warren GB, Toon PA, Birdsall NJ, Lee AG, Metcalfe JC. Complete control of the lipid environment of membrane-bound proteins: application to a calcium transport system. FEBS Lett 1974; 41:122-4. [PMID: 4277416 DOI: 10.1016/0014-5793(74)80969-5] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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147
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Levine YK, Birdsall NJM, Lee AG, Metcalfe JC, Partington P, Roberts GCK. Calculation of dipolar nuclear magnetic relaxation times in molecules with multiple internal rotations. II. Theoretical results for anisotropic over‐all motion of the molecule, and comparison with13C relaxation times inn‐alkanes andn‐alkyl bromides. J Chem Phys 1974. [DOI: 10.1063/1.1681458] [Citation(s) in RCA: 123] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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148
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Warren GB, Toon PA, Birdsall NJ, Lee AG, Metcalfe JC. Reconstitution of a calcium pump using defined membrane components. Proc Natl Acad Sci U S A 1974; 71:622-6. [PMID: 4274560 PMCID: PMC388063 DOI: 10.1073/pnas.71.3.622] [Citation(s) in RCA: 296] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
A (Mg(2+) + Ca(2+))ATPase (ATP phosphohydrolase, EC 3.6.1.3) has been purified from sarcoplasmic reticulum using a single step centrifugation procedure. The preparation is >95% pure by weight and contains only 25-30% of the lipid associated with the enzyme in native sarcoplasmic reticulum. The purified enzyme is unable to accumulate Ca(2+). Using a sedimentation-substitution technique, >98% of the lipid associated with the purified enzyme can be replaced by dioleoyl lecithin without grossly affecting the ATPase activity of the enzyme. The Ca(2+) pump can be restored to this dioleoyl lecithin-substituted enzyme by addition of excess sarcoplasmic reticulum lipids in the presence of cholate. Removal of the cholate by dialysis generates a system which accumulates Ca(2+) at a rate and to a level comparable to native sarcoplasmic reticulum. Significant reconstitution of the Ca(2+) pump can also be achieved using excess dioleoyl lecithin, but since the full expression of the capacity to accumulate Ca(2+) requires the presence of oxalate, these vesicles would appear to be more leaky than those reconstituted with an excess of sarcoplasmic reticulum lipids. Of about 90 lipid molecules which are associated with one molecule of ATPase in native sarcoplasmic reticulum, an average of less than one lipid molecule remains in these reconstituted systems. We have therefore achieved a fully functional Ca(2+) pump containing essentially a single protein and exogenous lipid.
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149
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150
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Lee AG, Birdsall NJ, Metcalfe JC. Measurement of fast lateral diffusion of lipids in vesicles and in biological membranes by 1 H nuclear magnetic resonance. Biochemistry 1973; 12:1650-9. [PMID: 4349407 DOI: 10.1021/bi00732a029] [Citation(s) in RCA: 118] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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