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PubMed1966

Effects of cystamine and cysteamine on the adenosine-triphosphatase activity and oxidative phosphorylation of rat-liver mitochondria.

1. Cystamine (2,2'-diaminodiethyl disulphide) caused an unmasking of mitochondrial adenosine triphosphatase and a leakage of Mg(2+) from the mitochondria, and decreased the stimulation of adenosine triphosphatase by 2,4-dinitrophenol. When Mg(2+) was added, cystamine potentiated the activation of adenosine triphosphatase by 2,4-dinitrophenol. 2. Cystamine was without effect on the adenosine triphosphatase of disrupted mitochondria. 3. Cystamine was moderately potent as an uncoupling agent and as an inhibitor of the [(32)P]P(i)-ATP exchange reaction. 4. Cysteamine (2-aminoethanethiol) was without the above effects, when special precautions were taken to counteract its autoxidation. 5. The effects of cystamine should probably be ascribed to its disulphide group, since the diamine cadaverine protected slightly against the loss of Mg(2+) and the decrease of 2,4-dinitrophenol-stimulated adenosine-triphosphatase activity caused by aging of the mitochondria. It is suggested that cystamine acts by a breakdown of mitochondrial permeability barriers.

Adenosine Triphosphatases↗

PubMed1966

The mode of inhibition by calcium of cell-membrane adenosine-triphosphatase activity.

1. The mechanism of the inhibition of Na(+)-plus-K(+)-activated adenosine triphosphatase by calcium was investigated with an enzyme preparation from rabbit kidney cortex and with membranes of human erythrocytes. 2. CaATP, rather than ionic Ca(2+), acts as a competitive inhibitor, competing with MgATP in the Na(+)-plus-K(+)-activated adenosine-triphosphatase reaction. 3. There appears to be no competition between calcium and Na(+) for the activation of adenosine triphosphatase. 4. The inhibition of Na(+)-plus-K(+)-activated adenosine triphosphatase of cell membranes by low concentrations of CaATP and the consequent need of intact cells to keep the cytoplasmic concentration of calcium low relative to that of magnesium suggests a raison d'être for the mitochondrial calcium pump.

Adenosine Triphosphatases↗

PubMed1973

Reconstitution of the energy-linked transhydrogenase activity in membranes from a mutant strain of Escherichia coli K12 lacking magnesium ion- or calcium ion-stimulated adenosine triphosphatase.

1. We have isolated a mutant of Escherichia coli K12 (strain AN295) that forms de-repressed amounts of Mg(2+),Ca(2+)-stimulated adenosine triphosphatase. 2. The Mg(2+),Ca(2+)-stimulated triphosphatase activity was separated from membrane preparations from strain AN295 by extraction with 5mm-Tris-HCl buffer containing EDTA and dithiothreitol, resulting in a loss of the ATP-dependent transhydrogenase activity. The non-energy-linked transhydrogenase activity remained in the membrane residue. 3. The solubilized Mg(2+),Ca(2+)-stimulated adenosine triphosphatase activity from strain AN295 was partially purified by repeated gel filtration. The addition of the purified Mg(2+),Ca(2+)-stimulated adenosine triphosphatase to the membrane residue from strain AN295 reactivated the ATP-dependent transhydrogenase activity. 4. Strain AN296, lacking Mg(2+),Ca(2+)-stimulated adenosine triphosphatase activity, was derived by transducing the mutant allele, uncA401, into strain AN295. The ATP-dependent transhydrogenase activity was lost but the non-energy linked transhydrogenase was retained. 5. The ATP-dependent transhydrogenase activity in membrane preparations from strain AN296 (uncA(-)) could not be re-activated by the purified Mg(2+),Ca(2+)-stimulated adenosine triphosphatase from strain AN295. However, after extraction by 5mm-Tris-HCl buffer containing EDTA and dithiothreitol, the ATP-dependent transhydrogenase activity could be re-activated by the addition of the purified Mg(2+),Ca(2+)-stimulated adenosine triphosphatase from strain AN295 to the membrane residue from strain AN296 (uncA(-)).

Adenosine Triphosphatases↗

PubMed1990

Alteration of sodium, potassium-adenosine triphosphatase activity in rabbit ciliary processes by cyclic adenosine monophosphate-dependent protein kinase.

The response of sodium, potassium-adenosine triphosphatase (Na,K-ATPase) to cyclic adenosine monophosphate (cAMP)-dependent protein kinase was examined in membranes obtained from rabbit iris-ciliary body. In the presence of the protein kinase together with 10(-5) M cAMP, Na,K-ATPase activity was reduced. No change in Na,K-ATPase activity was detected in response to the protein kinase without added cAMP. Likewise cAMP alone did not alter Na,K-ATPase activity. Reduction of Na,K-ATPase activity was also observed in the presence of the cAMP-dependent protein kinase catalytic subunit. The response of the enzyme to the kinase catalytic subunit was also examined in membranes obtained from rabbit ciliary processes. In the presence of 8 micrograms/ml of the catalytic subunit, ciliary process Na,K-ATPase activity was reduced by more than 50%. To examine whether other ATPases were suppressed by the protein kinase, calcium-stimulated ATPase activity was examined; its activity was stimulated by the catalytic subunit. To test whether the response of the ciliary process Na,K-ATPase is unique, experiments were also performed using membrane preparations from rabbit lens epithelium or rabbit kidney; the catalytic subunit significantly reduced the activity of Na,K-ATPase from the kidney but not the lens. These Na,K-ATPase studies suggest that in the iris-ciliary body, cAMP may alter sodium pump activity. In parallel 86Rb uptake studies, we observed that ouabain-inhibitable potassium uptake by intact pieces of iris-ciliary body was reduced by exogenous dibutryl cAMP or by forskolin.

Animals↗

PubMed1988

Adenosine triphosphatase in nerves and ganglia of rats with streptozotocin-induced diabetes or galactosaemia; effects of aldose reductase inhibition.

This study measured the ouabain-sensitive and ouabain-resistant adenosine triphosphatase activity in homogenates of the sciatic nerves and of pooled fourth and fifth lumbar dorsal root ganglia from rats fed 20% galactose or made diabetic with streptozotocin for either 4 or 8 weeks. Diabetes caused reductions in both fractions of sciatic nerve adenosine triphosphatase activity. After 8 weeks the ouabain-sensitive fraction was 54% of control (p less than 0.05) and the ouabain-resistant fraction was 57% of control (p less than 0.05). Galactose feeding more than doubled the ouabain-sensitive adenosine triphosphatase activity in the sciatic nerve (225% of control after 4 weeks, 215% of control after 8 weeks of galactose feeding, both p less than 0.01) and produced a progressive increase in the ouabain-resistant fraction (119% of control at 4 weeks (p less than 0.05) and 176% of control at 8 weeks (p less than 0.01)). In a group of rats fed galactose for 5 days, sciatic nerve ouabain-sensitive adenosine triphosphatase activity was 165% of control. Treatment with the aldose-reductase inhibitors tolrestat, ponalrestat or sorbinil prevented accumulation of polyol and depletion of myo-inositol in the sciatic nerves, indicating effective inhibition of aldose reductase. These drugs prevented completely the effect of galactose on the sciatic nerve adenosine triphosphatase activity, but had no significant effect on the reduction in adenosine triphosphatase activity in the sciatic nerves of diabetic rats. In the dorsal root ganglia galactose feeding had no measurable effect on the adenosine triphosphatase activity. Diabetes caused a modest numerical reduction in the ouabain-sensitive activity only.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphatases↗

PubMed1971

The effect of salts on catecholamine fluxes and adenosine triphosphatase activity in storage vesicles from the adrenal medulla.

1. Influx and efflux of catecholamine and adenosine triphosphatase activity in storage vesicles from the adrenal medulla were studied with dl-[(14)C]adrenaline in different media. 2. The lowest values for flux and adenosine triphosphatase activity were observed in sucrose media in which an ATP-dependent influx of catecholamine compensated for an efflux of the same magnitude. Efflux in the presence or absence of ATP was similar. 3. In media containing sodium succinate or glutarate adenosine triphosphatase activity was higher and the ATP-dependent influx of catecholamine was about twice that observed in iso-osmotic sucrose medium. In the presence of ATP influx and efflux of catecholamine were balanced; in its absence there was a net release of catecholamine, since efflux was more than twice the influx. Efflux in the presence or absence of ATP was similar. 4. In media containing sodium or potassium chloride and in the presence of ATP influx and adenosine triphosphatase activity were further enhanced, but in the absence of ATP there was no further increase in influx, since catecholamine was released with or without ATP at the same rate. Efflux was therefore twice as high in the presence of ATP as in its absence. 5. Sodium nitrate suppressed the ATP-dependent influx nearly completely, but caused a greatly enhanced efflux, which was twice as high in the presence of ATP as in its absence. 6. The extinction of vesicular suspensions remained unchanged in the presence of ATP under conditions where the catecholamine efflux was balanced by the influx. Under conditions where the efflux was not compensated by influx, the extinction of the suspensions decreased in the presence of ATP more than in its absence.

Adenosine Triphosphatases↗

PubMed2000

Potential role of vacuolar H-adenosine triphosphatase in neointimal formation in cultured human saphenous vein.

OBJECTIVE: Vacuolar H(+)-adenosine triphosphatase plays a pivotal role in pH regulation and molecular transport across the vacuolar membranes and is involved in cell proliferation and transformation. In the present study, possible involvement of vacuolar H(+)-adenosine triphosphatase in neointimal formation was investigated in an organ culture model of human saphenous vein. METHODS AND RESULTS: Cultured saphenous vein segments developed neointimal formation and marked thickening of the media within 14 days. Neointimal formation and medial thickening were completely inhibited by 10 nmol/L bafilomycin A(1), a selective inhibitor of vacuolar H(+)-adenosine triphosphatase, although structurally related macrolide antibiotics FK-506 and erythromycin were without an effect. The neointimal cells were positive for alpha-smooth muscle actin and vimentin but negative for desmin, indicative of myofibroblasts. The emergence of myofibroblasts was inhibited, and endothelial cells were preserved in the saphenous vein segments treated with bafilomycin A(1). Uptake of bromodeoxyuridine, a proliferation marker, by myofibroblasts was abrogated in the saphenous vein segments treated with 10 nmol/L bafilomycin A(1). Detection of apoptotic cells by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling concomitant with identification of desmin-expressing smooth muscle cells demonstrated that neointimal myofibroblasts, but not medial smooth muscle cells, that expressed desmin underwent apoptosis by treatment with bafilomycin A(1). CONCLUSIONS: These results suggest that vacuolar H(+)-adenosine triphosphatase may be involved in myofibroblast growth that contributes to neointimal formation and medial thickening in cultured human saphenous vein. Increased sensitivity of myofibroblasts, but not endothelial cells, and differentiated smooth muscle cells to bafilomycin A(1) may have potential therapeutic implications in the treatment for vein graft disease.

Actins↗

PubMed1972

Purification of an ion-stimulated adenosine triphosphatase from plant roots: association with plasma membranes.

A membrane-bound adenosine triphosphatase (EC 3.6.1.3) that requires Mg(++) and that is stimulated by monovalent ions has been purified 7- to 8-fold from homogenates of oat (Avena sativa L. Cult. Goodfield) roots by discontinuous sucrose-gradient centrifugation. The enzyme was substrate specific; adenosine triphosphate was hydrolyzed 25 times more rapidly than other nucleoside triphosphates. The membrane fraction containing adenosine triphosphatase was enriched in plasma membranes, which were identified by the presence of a glucan synthetase (EC 2.4.1.12), a high sterol to phospholipid ratio, and by a stain consisting of periodic acid, chromic acid, and phosphotungstic acid that is specific for plant plasma membranes. Oat-root plasma membranes and the associated adenosine triphosphatase were purified on either a 6-layer discontinuous sucrose gradient or on a simplified gradient consisting of only two sucrose layers.These results represent the first demonstration that plant plasma membranes contain an adenosine triphosphatase that is activated by monovalent ions, and this finding further implicates the enzyme in the absorption of inorganic ions by plant roots.

Journal Article↗

PubMed1981

Visualization of nucleolar substructure in cultured human fibroblasts by magnesium-activated adenosine triphosphatase reaction.

Discrete sites of adenosine triphosphatase (ATPase) activity were demonstrated within the nucleoli of unfixed cultured human fibroblasts (IMR90, VA13, and AG2804 cells) by an adaptation, for electron microscopic cyto-chemistry, of Wachstein and Meisel's lead nitrate method. The majority of nucleoli contained more than one ATPase-positive region, but the total ATPase-positive material appeared to occupy only a minor portion of the nucleolar volume. These regions were roughly spherical with an irregular contour, and at times appeared to be components of perinucleolar chromatin or to be located adjacent to nucleolar interstices. The distribution of these regions within the nucleolus and their segregation by actinomycin D suggested that the ATPase-positive regions correspond to the fibrillar centers, which represent nucleolar organizer regions. The cytochemically demonstrable nucleolar ATPase was strictly dependent on the presence of divalent cations. Optimal reactions was seen at 5 mM Mg2+, but near optimal activity was obtained with lower concentrations of Mg2+ in the presence of Ca2+. Calcium alone and Mn2+ alone produced suboptimal reaction. Studies with different nucleoside phosphates as reaction substrates showed that the enzyme is specific for adenosine derivatives, ATP and dATP being equally good substrates. Guanosine triphosphate, cytidine triphosphate, uridine triphosphate, and d-thymidine triphosphate were ineffective as substrates, as were nucleoside mono- and diphosphates and other phosphate esters tested. It is suggested that the cytochemical ATPase reaction visualized the regions of the nucleolus in which ribosomal DNA of intranucleolar chromatin is undergoing conformational alterations.

Adenosine Triphosphatases↗

PubMed1983

Small-angle X-ray scattering study of adenosine triphosphatase from thermophilic bacterium PS3.

Adenosine triphosphatase from the thermophilic bacterium PS3(TF1) has been studied by solution X-ray scattering. A structural change in TF1 caused by the binding of ADP was observed by examining the difference between the radii of gyration of the unligated and ligated forms. The radius of gyration of the unligated TF1 was found to be 49.5 +/- 0.3 A, and it decreased by approximately 3% after ligation with ADP. The positions and the amplitudes of a subsidiary maximum and a shoulder in the scattering profile showed subtle change on nucleotide binding. The lower limit of the maximum length of TF1 was determined to be 165 A for the unligated form and 150 A for the ligated form. The shape analysis of TF1 was performed by model calculations for simple triaxial bodies or their complexes. Among the various models tested, the one that gave the best fit with the experimental data consisted of seven ellipsoids of revolution; six identical ellipsoids with semi-axes: a = b = 18.5 A and c = 74 A. arranged hexagonally, and the other with a = b = 28 A and c = 45 A, located below the other six on the 6-fold axis. On the basis of this model it was suggested that there is a structural change on ligation with nucleotides, consisting of a shrinkage of the six long ellipsoids by 6% along their major axes.

Adenosine Diphosphate↗

PubMed1966

Separation of adenosine diphosphate--adenosine triphosphate-exchange activity from the cerebral microsomal sodium-plus-potassium ion-stimulated adenosine triphosphatase.

1. A microsomal fraction from ox cerebral cortex catalysed [(14)C]ADP-ATP exchange at a speed similar to that at which it liberated P(i) from ATP in the presence of Na(+), K(+) and Mg(2+). 2. Repeated washing the fraction with MgATP solutions solubilized most of the exchange activity and left the adenosine triphosphatase insoluble and little changed in activity. The exchange activity was accompanied by negligible adenosine-triphosphatase activity and was enriched by precipitation at chosen pH and by DEAE-Sephadex. At no stage was its activity affected by Na(+), K(+) or ouabain. 3. The washed microsomal fraction was exposed to a variety of reagents; a sodium iodide-cysteine treatment increased both adenosine-triphosphatase and exchange activities, as also did a synthetic zeolite. Preparations were obtained with exchange activities less than 3% of their Na(+)-plus-K(+)-stimulated adenosine-triphosphatase activity. Some contribution to the residual exchange activity was made by an adenylate kinase. 4. Thus over 95% of the microsomal ADP-ATP-exchange activity does not take part in the Na(+)-plus-K(+)-stimulated adenosine-triphosphatase reaction. Participation of some of the residual 3% of the ADP-ATP-exchange activity has not been excluded, but there appears no firm evidence for its participation in the adenosine triphosphatase; the bearing of this conclusion on mechanisms proposed for the Na(+)-plus-K(+)-stimulated adenosine triphosphatase is indicated.

Adenine Nucleotides↗

PubMed1979

An active-site-directed adenosine triphosphate analogue binds to the beta-subunits of factor F1 mitochondrial adenosine triphosphatase with its triphosphate moiety.

The reaction of the mixed anhydride of [3H]ATP and mesitylenecarboxylic acid and soluble mitochondrial adenosine triphosphatase is accompanied by the covalent binding of one molecule of the inhibitor to a molecule of the enzyme and results in the inhibition of adenosine triphosphatase activity by more than 90%. The electrophoresis of adenosine triphosphatase modified by reaction with the mixed anhydride of [3H]ATP and mesitylenecarboxylic acid in polyacrylamide gel in the presence of sodium dodecyl sulphate showed that the inhibitor is bound to the beta-subunit of the enzyme. The results suggest that ATP may also bind to the beta-subunit of the adenosine triphosphatase with its triphosphate moiety.

Adenosine Triphosphatases↗

PubMed1965

The localization of adenosine triphosphatases in morphologically characterized subcellular fractions of guinea-pig brain.

1. The distribution of adenosine triphosphatase was studied in morphologically characterized subcellular fractions of guinea-pig brain. The conditions of homogenization were selected so as to favour the survival of nerve endings as organized structures. 2. A fraction consisting mainly of the external membranes of nerve endings was rich in a ouabain-sensitive Na(+)-K(+)-stimulated adenosine triphosphatase which closely resembled that present in the classical microsomal fraction studied by other workers, but which showed a higher specific activity. 3. A dinitrophenol-stimulated adenosine triphosphatase was located in the nerve-ending mitochondria. 4. The synaptic-vesicle fraction contained a small amount of adenosine triphosphatase that differed in its response to several ions and other compounds from the membrane, myelin and mitochondrial fractions, indicating freedom from contamination by these elements.

Acetylcholine↗

PubMed1973

The effects of environmental temperature on the properties of myofibrillar adenosine triphosphatase from various species of fish.

1. Myofibrillar adenosine triphosphatase (ATPase) activities were measured for white myotomal muscle of 19 species of fish. 2. The activity was measured at different temperatures and after periods of preincubation at 37 degrees C. 3. The inactivation half-life at 37 degrees C depended on environmental temperature, increasing as the temperature increased. 4. Cold-water fish had higher myofibrillar adenosine triphosphatase activity at low temperatures than had warm-water fish. 5. The significance of these results is discussed.

Adenosine Triphosphatases↗

PubMed1975

Phosphorylation by inorganic phosphate of sodium plus potassium ion transport adenosine triphosphatase. Four reactive states.

Native solium and potassium adenosine triphosphatase from guinea pig kidney accepted a phosphate group from radioactive inorganic phosphate to form an acyl phosphate bond at the active site in the presence or absence of sodium ion. Magnesium ion was always required. In the presence of sodium ion and absence of adenosine triphosphate, there was no phosphorylation by inorganic phosphate. Addition of unlabeled adenosine triphosphate produced a potassium-sensitive phosphoenzyme which exchanged its phosphate-group with radioactive inorganic phosphate. The dephosphoenzyme was an intermediate in this exchange. The rate constant for dephosphorylation was about 0.05 per second. Addition of rubidium ion, a congener of potassium ion, to the potassium-sensitive phosphoenzyme produced a phosphoenzyme labeled from inorganic phosphate with a corresponding rate constant of 0.26 per s. This was a rubidium-complexed phosphoenzyme. Addition of magnesium ion to potassium-sensitive phosphoenzyme converted it into insensitive phosphoenzyme, the splitting of which was not accelerated by potassium ion or by adenosine diphosphate. Its rate constant was 0.07 per s. In the absence of sodium ion and adenosine triphosphate, inorganic phosphate was incorporated directly into a similar insensitive phosphoenzyme. In the presence of potassium ion or rubidium ion, inorganic phosphate was incorporated into a potassium-complexed or rubidium-complexed phosphoenzyme which exchanged 32-P with inorganic phosphate completely in less than 3 s. Incorporation of inorganic phosphate into a complex of the enzyme with the inhibitor, ouabain, is already described in the literature. Its rate constant was about 0.02 per s. Thus there appear to be at least four reactive states of the phosphoenzyme which equilibrate measurably with inorganic phosphate, namely, potassium-sensitive phosphoenzyme, potassium-complexed phosphoenzyme, insensitive phosphoenzyme, and ouabain phosphoenzyme. Two of these reactive states are functional intermediates in native sodium and potassium ion transport adenosine triphosphatase. The results are compatible with control of the reactivity of the active site by conformational changes in the surrounding active center and with regulation of the energy level of the phosphate group according to the kind of monovalent cation bound to the enzyme.

Adenosine Triphosphatases↗

PubMed1972

Increased Membrane-bound Adenosine Triphosphatase Activity Accompanying Development of Enhanced Solute Uptake in Washed Corn Root Tissue.

Washing of excised corn (Zea mays L., variety WF9xM14) root tissue is accompanied by an increase in (Mg(2+) + K(+))-stimulated adenosine triphosphatase. This is the adenosine triphosphatase described by Fisher, Hansen, and Hodges as positively correlated with ion accumulation rates. The increase in activity is confined to the microsomal fraction. A close parallel exists between increases in adenosine triphosphatase and phosphate absorption, and they respond similarly to inhibitors of RNA and protein synthesis. However, the amplitude of change is much smaller in adenosine triphosphatase. Possible reasons for this discrepancy are discussed.

Journal Article↗

PubMed1963

NUTRITION AND METABOLISM OF MARINE BACTERIA. XII. ION ACTIVATION OF ADENOSINE TRIPHOSPHATASE IN MEMBRANES OF MARINE BACTERIAL CELLS.

Drapeau, Gabriel R., (Macdonald College of McGill University, Quebec, Canada) and Robert A. MacLeod. Nutrition and metabolism of marine bacteria. XII. Ion activation of adenosine triphosphatase in membranes of marine bacterial cells. J. Bacteriol. 85:1413-1419. 1963.-Isolated membranes of two species of marine bacteria, a Pseudomonas and a Cytophaga, have been shown to possess adenosine triphosphatase activity. The optimal pH for enzyme action of both organisms was 8.8. The enzyme system was found to be capable of splitting inorganic o-phosphate from adenosine triphosphate (ATP), adenosine diphosphate, adenosine monophosphate, and inosine triphosphate but not from inorganic pyrophosphate. Mg(++) was required for enzyme activity; with the Pseudomonas species, the optimal Mg(++) to ATP ratio was 1:1. Ca(++) could not replace Mg(++). In the presence of the optimal concentration of Mg(++), the enzyme system was further stimulated, nonspecifically, by a number of different salts. Maximal activation was achieved at an ionic strength of 0.3 to 0.4. No evidence of an adenosine triphosphatase specifically activated by a combination of Na(+) and K(+) was obtained with either organism. No effect of ouabain on either the membrane adenosine triphosphatase activity or Na(+) transport by whole cells could be detected. The results suggest that the mechanism of ion regulation in marine bacterial cells is different from that in animal cells.

Adenine Nucleotides↗

PubMed1987

Membrane adenosine triphosphatase in synchronous cultures of Rhodobacter sphaeroides.

Studies of intracytoplasmic membrane biogenesis utilizing synchronized cultures of Rhodobacter sphaeroides have revealed that most intracytoplasmic membrane proteins accumulate continuously throughout the cell cycle while new phospholipid appears discontinuously within the intracytoplasmic membrane. The resulting changes in the structure of the membrane lipids was proposed to influence the activities of enzymes associated with the intracytoplasmic membranes (Wraight, C.A., Leuking, D.R., Fraley, R.T. and Kaplan, S. (1978) J. Biol. Chem. 253, 465-471). We have extended the study of intracytoplasmic membrane biogenesis in R. sphaeroides to include the membrane adenosine triphosphatase. The membrane bound Mg2+-dependent, oligomycin-sensitive adenosine triphosphatase activity was measured throughout the cell cycle for steady-state synchronized cells of R. sphaeroides and found to accumulate discontinuously. Following treatment with an uncoupling reagent (2,4-dinitrophenol) the intracytoplasmic membrane associated adenosine triphosphatase activity was stimulated uniformly in membranes isolated at different stages of the cell cycle. The adenosine triphosphatase was also measured by quantitative immunoblots utilizing specific antibody to compare the enzyme activity and enzyme protein mass. Immunologic measurement of the adenosine triphosphatase in isolated membranes indicated a constant ratio of enzyme to chromatophore protein exists during the cell cycle in contrast to the discontinuous accumulation of adenosine triphosphatase activity. These results are discussed in light of the cell-cycle specific synthesis of the intracytoplasmic membrane.

Adenosine Triphosphatases↗