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Alfarouk KO, Ahmed SBM, Elliott RL, Benoit A, Alqahtani SS, Ibrahim ME, Bashir AHH, Alhoufie STS, Elhassan GO, Wales CC, Schwartz LH, Ali HS, Ahmed A, Forde PF, Devesa J, Cardone RA, Fais S, Harguindey S, Reshkin SJ. The Pentose Phosphate Pathway Dynamics in Cancer and Its Dependency on Intracellular pH. Metabolites 2020; 10:E285. [PMID: 32664469 PMCID: PMC7407102 DOI: 10.3390/metabo10070285] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 07/02/2020] [Accepted: 07/06/2020] [Indexed: 12/21/2022] Open
Abstract
The Pentose Phosphate Pathway (PPP) is one of the key metabolic pathways occurring in living cells to produce energy and maintain cellular homeostasis. Cancer cells have higher cytoplasmic utilization of glucose (glycolysis), even in the presence of oxygen; this is known as the "Warburg Effect". However, cytoplasmic glucose utilization can also occur in cancer through the PPP. This pathway contributes to cancer cells by operating in many different ways: (i) as a defense mechanism via the reduced form of nicotinamide adenine dinucleotide phosphate (NADPH) to prevent apoptosis, (ii) as a provision for the maintenance of energy by intermediate glycolysis, (iii) by increasing genomic material to the cellular pool of nucleic acid bases, (iv) by promoting survival through increasing glycolysis, and so increasing acid production, and (v) by inducing cellular proliferation by the synthesis of nucleic acid, fatty acid, and amino acid. Each step of the PPP can be upregulated in some types of cancer but not in others. An interesting aspect of this metabolic pathway is the shared regulation of the glycolytic and PPP pathways by intracellular pH (pHi). Indeed, as with glycolysis, the optimum activity of the enzymes driving the PPP occurs at an alkaline pHi, which is compatible with the cytoplasmic pH of cancer cells. Here, we outline each step of the PPP and discuss its possible correlation with cancer.
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Affiliation(s)
- Khalid O. Alfarouk
- Alfarouk Biomedical Research LLC, Temple Terrace, FL 33617, USA
- American Biosciences Inc., New York, NY 10913, USA;
- Al-Ghad International College for Applied Medical Sciences, Al-Madinah Al-Munawarah 42316, Saudi Arabia
| | | | - Robert L. Elliott
- The Elliott-Elliott-Baucom Breast Cancer Research and Treatment Center, Baton Rouge, LA 70806, USA;
- The Sallie A. Burdine Breast Foundation, Baton Rouge, LA 70806, USA;
| | - Amanda Benoit
- The Sallie A. Burdine Breast Foundation, Baton Rouge, LA 70806, USA;
| | - Saad S. Alqahtani
- Clinical Pharmacy Department, College of Pharmacy, Jazan University, Jazan 45142, Saudi Arabia;
| | - Muntaser E. Ibrahim
- Institute of Endemic Diseases, University of Khartoum, Khartoum 11111, Sudan; (M.E.I.); (A.H.H.B.)
| | - Adil H. H. Bashir
- Institute of Endemic Diseases, University of Khartoum, Khartoum 11111, Sudan; (M.E.I.); (A.H.H.B.)
| | - Sari T. S. Alhoufie
- Department of Clinical Laboratory Sciences, Faculty of Applied Medical Sciences, Taibah University, Al-Madinah Al-Munwarah 42353, Saudi Arabia;
| | - Gamal O. Elhassan
- Unaizah College of Pharmacy, Qassim University, Unaizah 56264, Saudi Arabia;
| | | | | | - Heyam S. Ali
- Department of Pharmaceutics, Faculty of Pharmacy, University of Khartoum, Khartoum 11111, Sudan;
| | - Ahmed Ahmed
- Department of Oesphogastric and General Surgery, University Hospitals of Leicester, Leicester LE5 4PW, UK;
| | - Patrick F. Forde
- CancerResearch@UCC, Western Gateway Building, University College Cork, Cork T12 XF62, Ireland;
| | - Jesus Devesa
- Scientific Direction, Foltra Medical Centre, Travesía de Montouto 24, 15886 Teo, Spain;
| | - Rosa A. Cardone
- Department of Biosciences, Biotechnologies, and Biopharmaceutics, University of Bari, 90126 Bari, Italy; (R.A.C.); (S.J.R.)
| | - Stefano Fais
- Department of Oncology and Molecular Medicine, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy;
| | - Salvador Harguindey
- Department of Oncology, Institute for Clinical Biology and Metabolism, 01004 Vitoria, Spain;
| | - Stephan J. Reshkin
- Department of Biosciences, Biotechnologies, and Biopharmaceutics, University of Bari, 90126 Bari, Italy; (R.A.C.); (S.J.R.)
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Anderson BM, Wise DJ, Anderson CD. Azotobacter vinelandii glucose 6-phosphate dehydrogenase properties of NAD- and NADP-linked reactions. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1340:268-76. [PMID: 9252113 DOI: 10.1016/s0167-4838(97)00057-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Glucose 6-phosphate oxidation, catalyzed by purified Azotobacter vinelandii glucose 6-phosphate dehydrogenase, was studied with respect to the selective utilization of NAD, NADP, thionicotinamide adenine dinucleotide or thionicotinamide adenine dinucleotide phosphate as coenzyme. A sigmoidal relationship was observed for the effect of substrate concentration on initial velocities when either NAD, NADP or thionicotinamide adenine dinucleotide was used as coenzyme, with N values from the Hill equation equalling 2.0, 1.7, and 1.7, respectively. The thionicotinamide analogs of NAD and NADP both functioned as coenzyme-competitive inhibitors of the enzyme-catalyzed NAD- and NADP-linked reactions. A dual wavelength assay, using a combination of NADP and thio-NAD, was established and was used to demonstrate that increasing glucose 6-phosphate concentration did not change the enzyme preference for the coenzyme form used. Sigmoidal relationships were observed for reduction of both dinucleotides, and N values were the same as those observed when each dinucleotide was studied as the only coenzyme form present in reaction mixtures. Using the dual wavelength assay, inhibition by isocitrate, 6-phosphogluconate, ATP, and palmitoyl-CoA was shown to be equally effective in both NAD- and NADP-linked reactions. An enzyme activator, glucosamine 6-phosphate, altered the glucose 6-phosphate sigmoidicity through activation at low substrate concentrations.
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Affiliation(s)
- B M Anderson
- Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg 20461-0308, USA.
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Lee WT, Levy HR. Lysine-21 of Leuconostoc mesenteroides glucose 6-phosphate dehydrogenase participates in substrate binding through charge-charge interaction. Protein Sci 1992; 1:329-34. [PMID: 1304341 PMCID: PMC2142207 DOI: 10.1002/pro.5560010304] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Leuconostoc mesenteroides glucose 6-phosphate dehydrogenase (G6PD) was isolated in high yield and purified to homogeneity from a newly constructed strain of Escherichia coli which lacks its own glucose 6-phosphate dehydrogenase gene. Lys-21 is one of two lysyl residues in the enzyme previously modified by the affinity labels pyridoxal 5'-phosphate and pyridoxal 5'-diphosphate-5'-adenosine, which are competitive inhibitors of the enzyme with respect to glucose 6-phosphate (LaDine, J.R., Carlow, D., Lee, W.T., Cross, R.L., Flynn, T.G., & Levy, H.R., 1991, J. Biol. Chem. 266, 5558-5562). K21R and K21Q mutants of the enzyme were purified to homogeneity and characterized kinetically to determine the function of Lys-21. Both mutant enzymes showed increased Km-values for glucose 6-phosphate compared to wild-type enzyme: 1.4-fold (NAD-linked reaction) and 2.1-fold (NADP-linked reaction) for the K21R enzyme, and 36-fold (NAD-linked reaction) and 53-fold (NADP-linked reaction) for the K21Q enzyme. The Km for NADP+ was unchanged in both mutant enzymes. The Km for NAD+ was increased 1.5- and 3.2-fold, compared to the wild-type enzyme, in the K21R and K21Q enzymes, respectively. For the K21R enzyme the kcat for the NAD- and NADP-linked reactions was unchanged. The kcat for the K21Q enzyme was increased in the NAD-linked reaction by 26% and decreased by 30% in the NADP-linked reaction from the values for the wild-type enzyme. The data are consistent with Lys-21 participating in the binding of the phosphate group of the substrate to the enzyme via charge-charge interaction.
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Affiliation(s)
- W T Lee
- Department of Biology, Syracuse University, New York 13244-1220
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Levy HR, Cook C. Purification and properties of NADP-linked glucose-6-phosphate dehydrogenase from Acetobacter hansenii (Acetobacter xylinum). Arch Biochem Biophys 1991; 291:161-7. [PMID: 1929428 DOI: 10.1016/0003-9861(91)90119-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The NADP-linked glucose-6-phosphate dehydrogenase from Acetobacter hansenii (formerly known as Acetobacter xylinum) has been purified to apparent homogeneity. The sequence of the 10 N-terminal amino acids was determined. The subunit molecular weight of the enzyme is 53,000 as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis; gel filtration studies under nondenaturing conditions revealed that the molecular weight of the enzyme is 200,000 to 220,000 at pH 6.5 and 9.5, suggesting that the native enzyme is a tetramer. Specificity studies at both pH 6.5 and 9.5 demonstrated that the enzyme is a typical NADP-preferring glucose-6-phosphate dehydrogenase. The enzyme's catalytic activity increases with increasing pH, kcat being approximately 4 times greater at pH 9.5 than at pH 6.7 and the Km for NADP+ being 3 times lower at the higher pH; but the Km for glucose 6-phosphate is nearly 20 times higher at pH 9.5 than at pH 6.7, suggesting that the enzyme is catalytically more efficient at the lower pH. At pH 6.7, initial velocity measurements, product inhibition by NADPH, and inhibition by glucosamine 6-phosphate yielded results that were consistent with a steady-state random mechanism. At pH 9.5, steady-state kinetic analyses suggested that the mechanism is ordered, with coenzyme binding first, but nonlinear double-reciprocal plots were observed in the presence of NADPH when glucose 6-phosphate was varied and a complete kinetic analysis was not undertaken. Among several nucleotides and potential inhibitory ligands examined, only 2',5'-ADP inhibited the enzyme significantly.
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Affiliation(s)
- H R Levy
- Department of Biology, Syracuse University, New York 13244
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Anderson BM, Anderson CD. Preparation and characterization of the NAD vinylogue, 3-pyridylacryloamide adenine dinucleotide. Anal Biochem 1991; 195:57-62. [PMID: 1888017 DOI: 10.1016/0003-2697(91)90294-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The vinylogue of NAD, 3-pyridylacryloamide adenine dinucleotide, was prepared from NAD and 3-pyridylacryloamide through the snake venom NADase-catalyzed transglycosidation reaction. The analog, purified by ion-exchange chromatography, was obtained in a 55% yield. The cyanide adduct and reduced form of the analog exhibited absorbance maxima at 358 nm and 378 nm, respectively, with extinction coefficients in each case being 2.3-times higher than those reported for the corresponding NAD derivatives. 3-Pyridylacryloamide adenine dinucleotide served as a coenzyme with bovine liver glutamic dehydrogenase and to a lesser extent with malate and lactate dehydrogenases. The analog was not reduced in reactions catalyzed by yeast and horse liver alcohol dehydrogenases, sheep liver sorbitol dehydrogenase, and rabbit muscle glycerophosphate dehydrogenase. Substitution of the pyridylacryloamide analogs for NAD and NADH in the assay of substrates for glutamic dehydrogenase was demonstrated.
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Affiliation(s)
- B M Anderson
- Department of Biochemistry and Nutrition, Virginia Polytechnic Institute and State University, Blacksburg 24061
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Skorkowski EF, Storey KB. Regulation of coenzyme utilization by mitochondrial NAD(P)-dependent malic enzyme. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1990; 22:471-5. [PMID: 2347425 DOI: 10.1016/0020-711x(90)90259-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
1. Skeletal muscle mitochondrial NAD(P)-dependent malic enzyme [EC 1.1.1. 39, L-malate:NAD+ oxidoreductase (decarboxylating)] from herring could use both coenzymes, NAD and NADP, in a similar manner. 2. The coenzyme preference of mitochondrial NAD(P)-dependent malic enzyme was probed using dual wavelength spectroscopy and pairing the natural coenzymes, NAD or NADP with their respective thionicotinamide analogues, s-NADP or s-NAD, that have absorbance maxima in reduced forms at 400 nm. 3. s-NAD and s-NADP were found to be good alternate substrates for NAD(P)-dependent malic enzyme, the apparent Km values for the thioderivatives were similar to those of the corresponding natural coenzymes. 4. ATP produced greater inhibition of the NAD or s-NAD linked reactions than of the NADP or s-NADP-linked reactions of skeletal muscle mitochondrial NAD(P)-dependent malic enzyme. 5. At 5 mM malate concentration and in the presence of 2 mM ATP the NADP-linked reaction is favoured and the activity ratios, V(s-NADP)/V(NAD) or V(NADP)/V(s-NAD), are 6 and 26, respectively.
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Bautista JM, Garrido-Pertierra A, Soler G. Glucose-6-phosphate dehydrogenase from Dicentrarchus labrax liver: kinetic mechanism and kinetics of NADPH inhibition. BIOCHIMICA ET BIOPHYSICA ACTA 1988; 967:354-63. [PMID: 3196755 DOI: 10.1016/0304-4165(88)90098-0] [Citation(s) in RCA: 76] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The kinetic mechanism of the reaction catalyzed by glucose-6-phosphate dehydrogenase (EC 1.1.1.49) from Dicentrarchus labrax liver was examined using initial velocity studies, NADPH and glucosamine 6-phosphate inhibition and alternate coenzyme experiments. The results are consistent with a steady-state ordered sequential mechanism in which NADP+ binds first to the enzyme and NADPH is released last. Replots of NADPH inhibition show an uncommon parabolic pattern for this enzyme that has not been previously described. A kinetic model is proposed in agreement with our kinetic results and with previously published structural studies (Bautista et al. (1988) Biochem. Soc. Trans. 16, 903-904). The kinetic mechanism presented provides a possible explanation for the regulation of the enzyme by the [NADPH]/[NADP+] ratio.
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Affiliation(s)
- J M Bautista
- Departamento de Bioquímica y Biologia Molecular y Genética, Universidad de Extremadura, Facultad de Veterinaria, Cáceres, Spain
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Bhadbhade MM, Adams MJ, Flynn TG, Levy HR. Sequence identity between a lysine-containing peptide from Leuconostoc mesenteroides glucose-6-phosphate dehydrogenase and an active site peptide from human erythrocyte glucose-6-phosphate dehydrogenase. FEBS Lett 1987; 211:243-6. [PMID: 3100332 DOI: 10.1016/0014-5793(87)81445-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Peptides recently isolated and sequenced from a bacterial (Leuconostoc mesenteroides) glucose-6-phosphate dehydrogenase are remarkably homologous to an active site region of the human erythrocyte enzyme, although the enzymes differ in their overall amino acid composition and kinetic properties. The computer program ALIGN, used to determine the best alignment between the two enzyme sequences, gives match-scores which are statistically highly significant.
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Adams MJ, Levy HR, Moffat K. Crystallization and preliminary x-ray data for glucose-6-phosphate dehydrogenase from Leuconostoc mesenteroides. J Biol Chem 1983. [DOI: 10.1016/s0021-9258(20)81975-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Levy HR, Christoff M, Ingulli J, Ho EM. Glucose-6-phosphate dehydrogenase from Leuconostoc mesenteroides: revised kinetic mechanism and kinetics of ATP inhibition. Arch Biochem Biophys 1983; 222:473-88. [PMID: 6847197 DOI: 10.1016/0003-9861(83)90546-5] [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: 01/22/2023]
Abstract
The kinetic mechanisms of the NAD- and NADP-linked reactions catalyzed by glucose-6-phosphate dehydrogenase from Leuconostoc mesenteroides were examined using product inhibition, dead-end inhibition and alternate substrate experiments. The results are consistent with a steady-state random mechanism for the NAD-linked and an ordered, sequential mechanism with NADP+ binding first for the NADP-linked reaction. Thus, the enzyme can bind NADP+, NAD+, and glucose 6-phosphate, but the enzyme-glucose 6-phosphate complex can react only with NAD+, not with NADP+. This affects the rate equation for the NADP-linked reaction by introducing a term for a dead-end enzyme-glucose 6-phosphate complex. The kinetic mechanisms represent revisions of those proposed previously (C. Olive, M.E. Geroch, and H.R. Levy, 1971, J. Biol. Chem. 246, 2047-2057) and provide a kinetic basis for the regulation of coenzyme utilization of the enzyme by glucose 6-phosphate concentration (H.R. Levy, and G.H. Daouk, 1979, J. Biol. Chem. 254, 4843-4847) and NADPH/NADP+ concentration ratios (H.R. Levy, G.H. Daouk, and M.A. Katopes, 1979, Arch, Biochem. Biophys. 198, 406-413). The kinetic mechanisms were found to be the same at pH 6.2 and pH 7.8. The kinetics of ATP inhibition of the NAD- and NADP-linked reactions were examined at pH 6.2 and pH 7.8. The results are interpreted in terms of ATP addition to binary enzyme-coenzyme and enzyme-glucose 6-phosphate complexes.
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Male KB, Storey KB. Regulation of coenzyme utilization by bovine liver glutamate dehydrogenase: investigations using thionicotinamide analogues of NAD and NADP in a dual wavelength assay. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1982; 14:1083-9. [PMID: 7173489 DOI: 10.1016/0020-711x(82)90165-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
1. The coenzyme preference of bovine liver glutamate dehydrogenase (GDH) was probed using dual wavelength spectroscopy and pairing the thionicotinamide analogues, S-NAD or S-NADP (which have absorbance maxima at 400 nm), with the natural coenzymes, NADP or NAD. 2. S-NAD and S-NADP were found to be good alternate substrates for GDH: the apparent Km's for the thioderivatives were similar to those of the corresponding natural coenzymes, the apparent Km's for glutamate were unaltered by the substitution of the thioderivatives, and the effects of inhibitors and activators on S-NAD or S-NADP kinetics were qualitatively the same as those found for NAD or NADP, respectively. 3. Dual wavelength assays paired NAD and S-NADP or S-NAD and NADP to study the simultaneous reduction of the two coenzymes. Conditions of increasing glutamate concentrations produced differential effects on the rates of the NAD vs NADP reactions, the result, with either nucleotide pair, promoting the NADP linked reaction. 4. Activators and inhibitors of the GDH reaction also showed differential effects upon the NAD vs NADP linked reaction rates in the dual wavelength assay. ADP and leucine, which activate both the NAD and the NADP linked reactions in single coenzyme assays, preferentially activate the NADP or S-NADP linked reactions in the dual nucleotide assays. GTP produced greater inhibition of the NAD or S-NAD linked reactions than of the NADP or S-NADP reactions while ATP inhibited NAD or S-NAD reactions and activated NADP or S-NADP reactions. The net effect of all metabolite modulators was to promote the NADP linked reaction by decreasing the activity ratios, v(NAD)/v(S-NADP) or v(S-NAD)/v(NADP). 5. The results are consistent with the suggestion that NADP is the preferred coenzyme for the oxidative deamination of glutamate by GDH even though the enzyme is capable of utilizing either coenzyme in vitro.
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Cox C, Camus P, Duvivier J. An enzymatic cycling procedure for NAD+ using an irreversible reaction with NAD+-peroxidase. Anal Biochem 1982; 119:185-93. [PMID: 6803610 DOI: 10.1016/0003-2697(82)90684-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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Shreve D, Levy H. Kinetic mechanism of glucose-6-phosphate dehydrogenase from the lactating rat mammary gland. Implications for regulation. J Biol Chem 1980. [DOI: 10.1016/s0021-9258(19)85788-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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