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Sengupta S, Chaudhuri P, Lahiri S, Dutta T, Banerjee S, Majhi R, Ghosh AK. Possible regulation of trehalose metabolism by methylation in Saccharomyces cerevisiae. J Cell Physiol 2010; 226:158-64. [DOI: 10.1002/jcp.22317] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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2
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Chen Y, McQuade KJ, Guan XJ, Thomason PA, Wert MS, Stock JB, Cox EC. Isoprenylcysteine carboxy methylation is essential for development in Dictyostelium discoideum. Mol Biol Cell 2007; 18:4106-18. [PMID: 17699599 PMCID: PMC1995708 DOI: 10.1091/mbc.e06-11-1006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Members of the Ras superfamily of small GTPases and the heterotrimeric G protein gamma subunit are methylated on their carboxy-terminal cysteine residues by isoprenylcysteine methyltransferase. In Dictyostelium discoideum, small GTPase methylation occurs seconds after stimulation of starving cells by cAMP and returns quickly to basal levels, suggesting an important role in cAMP-dependent signaling. Deleting the isoprenylcysteine methyltransferase-encoding gene causes dramatic defects. Starving mutant cells do not propagate cAMP waves in a sustained manner, and they do not aggregate. Motility is rescued when cells are pulsed with exogenous cAMP, or coplated with wild-type cells, but the rescued cells exhibit altered polarity. cAMP-pulsed methyltransferase-deficient cells that have aggregated fail to differentiate, but mutant cells plated in a wild-type background are able to do so. Localization of and signaling by RasG is altered in the mutant. Localization of the heterotrimeric Ggamma protein subunit was normal, but signaling was altered in mutant cells. These data indicate that isoprenylcysteine methylation is required for intercellular signaling and development in Dictyostelium.
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Affiliation(s)
- Ying Chen
- *Department of Molecular Biology, Princeton University, Princeton, NJ 08544; and
| | - Kyle J. McQuade
- *Department of Molecular Biology, Princeton University, Princeton, NJ 08544; and
- Department of Biology, Mesa State College, Grand Junction, CO 81501
| | - Xiao-Juan Guan
- *Department of Molecular Biology, Princeton University, Princeton, NJ 08544; and
| | - Peter A. Thomason
- *Department of Molecular Biology, Princeton University, Princeton, NJ 08544; and
| | - Michael S. Wert
- *Department of Molecular Biology, Princeton University, Princeton, NJ 08544; and
| | - Jeffry B. Stock
- *Department of Molecular Biology, Princeton University, Princeton, NJ 08544; and
| | - Edward C. Cox
- *Department of Molecular Biology, Princeton University, Princeton, NJ 08544; and
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7 Postisoprenylation protein processing: CXXX (CaaX) endoproteases and isoprenylcysteine carboxyl methyltransferase. PROTEIN LIPIDATION 2001. [DOI: 10.1016/s1874-6047(01)80020-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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4
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Becchetti A, Kemendy AE, Stockand JD, Sariban-Sohraby S, Eaton DC. Methylation increases the open probability of the epithelial sodium channel in A6 epithelia. J Biol Chem 2000; 275:16550-9. [PMID: 10747971 DOI: 10.1074/jbc.m000954200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We used single channel methods on A6 renal cells to study the regulation by methylation reactions of epithelial sodium channels. 3-Deazaadenosine (3-DZA), a methyltransferase blocker, produced a 5-fold decrease in sodium transport and a 6-fold decrease in apical sodium channel activity by decreasing channel open probability (P(o)). 3-Deazaadenosine also blocked the increase in channel open probability associated with addition of aldosterone. Sodium channel activity in excised "inside-out" patches usually decreased within 1-2 min; in the presence of S-adenosyl-l-methionine (AdoMet), activity persisted for 5-8 min. Sodium channel mean time open (t(open)) before and after patch excision was higher in the presence of AdoMet than in untreated excised patches but less than t(open) in cell-attached patches. Sodium channel activity in excised patches exposed to both AdoMet and GTP usually remained stable for more than 10 min, and P(o) and the number of active channels per patch were close to values in cell-attached patches from untreated cells. These findings suggest that a methylation reaction contributes to the activity of epithelial sodium channels in A6 cells and is directed to some regulatory element closely connected with the channel, whose activity also depends on the presence of intracellular GTP.
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Affiliation(s)
- A Becchetti
- Department of Physiology and the Center for Cell & Molecular Signaling, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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5
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Sariban-Sohraby S. Chapter 6 Role of G Proteins in the Regulation of Apical Membrane Sodium Permeability by Aldosterone in Epithelia. CURRENT TOPICS IN MEMBRANES 1999. [DOI: 10.1016/s0070-2161(08)60954-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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6
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Desrosiers RR, Béliveau R. Regulation by GTPgammaS of protein carboxylmethyltransferase activity in kidney brush border membranes. Arch Biochem Biophys 1998; 351:149-58. [PMID: 9514644 DOI: 10.1006/abbi.1997.0538] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The increase in carboxyl methylation induced by guanosine 5',3-O-(thio)triphosphate (GTPgammaS) in brush border membranes from rat kidney cortex was studied, and the methyltransferase activities affected by this nucleotide analog were identified. Addition of GTPgammaS to brush border membranes stimulated the carboxyl methylation in a time-dependent manner while adenosine and guanine nucleotides were ineffective. The GTPgammaS-dependent carboxyl methylation was inhibited by the chelating agents EDTA (63%) and 1,10-phenanthroline (68%), suggesting that this activity required divalent cations. The methyl ester groups induced by the addition of GTPgammaS to brush border membranes were unstable, with about 80% of them hydrolyzed following 1 h incubation at 37 degrees C. The GTPgammaS stimulation of the carboxyl methylation in brush border membranes was unaffected by the detergent 3-[(3cholamido)-dimethylammonio]-1-propanesulfonic acid up to a concentration of 0.4% (w/v). At this latter detergent concentration, the activity of prenylated protein methyltransferase (PPMT) was strongly inhibited and that of l-isoaspartyl/d-aspartylmethyltransferase (PIMT) was increased twofold, as measured with their respective exogenous substrates, N-acetyl-S-farnesyl cysteine and ovalbumin. GTPgammaS increased the methylation of several substrates in brush border membranes. The induced methylation in substrates migrating between 20 and 36 kDa was strongly decreased by the competitive inhibitor farnesylthioacetic acid, a synthetic farnesylated substrate for PPMT, while a delta-sleep-inducing peptide containing an L-isoaspartyl residue inhibited that of substrates with molecular weights above 36 kDa, suggesting that PIMT activity was also involved. This interpretation was strengthened by the observation that the increased methylation induced by GTPgammaS in these membrane substrates was completely lost following their analysis by gel electrophoresis under alkaline conditions. Taken together, these results indicate that both PPMT and PIMT activities are regulated by guanine nucleotides in brush border membranes of rat kidney.
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Affiliation(s)
- R R Desrosiers
- Département de chimie-biochimie, et Centre d'oncologie Charles Bruneau, Université du Québec à Montréal, Hôpital Sainte-Justine, Succursale Centre-ville, Montréal, Québec, H3C 3P8, Canada
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7
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Backlund PS. Post-translational processing of RhoA. Carboxyl methylation of the carboxyl-terminal prenylcysteine increases the half-life of Rhoa. J Biol Chem 1997; 272:33175-80. [PMID: 9407105 DOI: 10.1074/jbc.272.52.33175] [Citation(s) in RCA: 76] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
RhoA and related GTP-binding proteins are modified post-translationally at their carboxyl terminus to form a prenylcysteine methyl ester. The synthesis and post-translational modification of RhoA and Cdc42 were examined in the RAW264 macrophage cell line, and the effect of carboxyl methylation on protein turnover was determined. Cells were labeled with [35S]cysteine, and RhoA or Cdc42 was immunoprecipitated with specific antibodies. Both RhoA and Cdc42 were methylated rapidly in control cells, with little accumulation of unmethylated protein. Carboxyl methylation of RhoA was inhibited by incubation of cells with a carbocyclic adenosine analog, 3-deazaaristeromycin, resulting in the accumulation of unmethylated RhoA. Under these conditions, Cdc42 methylation was inhibited only partially. When methylation was inhibited, the RhoA half-life decreased from 31 to 12 h, and the Cdc42 half-life decreased from 15 to 11 h. The increased degradation of unmethylated RhoA demonstrates a novel function for carboxyl-terminal prenylcysteine carboxyl methylation in protecting RhoA and related proteins from degradation.
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Affiliation(s)
- P S Backlund
- Laboratory of General and Comparative Biochemistry, National Institute of Mental Health, Bethesda, Maryland 20892, USA.
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8
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Sariban-Sohraby S, Fisher RS. Guanine nucleotide-dependent carboxymethylation: a pathway for aldosterone modulation of apical Na+ permeability in epithelia. Kidney Int 1995; 48:965-9. [PMID: 8569106 DOI: 10.1038/ki.1995.378] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- S Sariban-Sohraby
- Laboratoire de Physiopathologie, Université Libre de Bruxelles, Belgium
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9
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Affiliation(s)
- C Volker
- Department of Molecular Biology and Chemistry, Lewis Thomas Laboratory, Princeton University, New Jersey 08544, USA
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10
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Volker C, Pillinger MH, Philips MR, Stock JB. Prenylcysteine analogs to study function of carboxylmethylation in signal transduction. Methods Enzymol 1995; 250:216-25. [PMID: 7651153 DOI: 10.1016/0076-6879(95)50074-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Carboxylmethylation of ras-related proteins is stimulated immediately on exposure of myeloid cells to inflammatory agonists. When the methylation reaction is inhibited with prenylcysteine analogs, G-protein-mediated signal transduction responses are disrupted, but responses to phorbol ester, calcium ionophore, and phospholipase C (PLC) remain intact. Furthermore, prenylcysteine analogs block GTP gamma S-induced aggregation of permeabilized platelets. Together, these results suggest that protein prenylcysteine methylation can play a role in signal transduction. A number of studies with AdoMet antagonists have suggested a role for methylation in cell-cycle regulation and stimulus-response coupling. Because the compounds generally inhibit all cellular methylation events, however, their effects have been difficult to interpret. On the other hand, prenylcysteine analogs have proved to be specific inhibitors of protein prenylcysteine methylation, as opposed to other types of methylation reactions. This enables the segregation of the role of methylation at C-terminal prenylcysteine residues from methylation at other sites, such as the carboxyl terminus of the catalytic subunit of PP2A. It should be emphasized, however, that prenylcysteine tails of proteins may interact with other target sites in addition to the methyltransferase enzyme(s), and prenylcysteine analogs may compete for these sites as well. One cannot assume that the inhibition of a response by the drugs necessarily implicates the involvement of a prenylcysteine methylation reaction. Studies with the analogs must be interpreted in conjunction with other results to ascertain the locus of their effects.
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Affiliation(s)
- C Volker
- Department of Molecular Biology, Princeton University, New Jersey 08544, USA
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11
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Ismailov I, McDuffie J, Sariban-Sohraby S, Johnson J, Benos D. Carboxyl methylation activates purified renal amiloride-sensitive Na+ channels in planar lipid bilayers. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)31775-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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12
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Gingras D, Béliveau R. Cytosolic proteins of 21-23 kDa are methylated by kidney cortex membrane-associated C-terminal carboxyl methyltransferases. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1204:149-56. [PMID: 8142453 DOI: 10.1016/0167-4838(94)90002-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We have studied the effect of a soluble fraction from kidney cortex on the C-terminal carboxyl methylation of 21-23 kDa proteins catalyzed by membrane-associated methyltransferases. Addition of soluble proteins to isolated luminal, antiluminal and intracellular membranes resulted in a large increase in the methylation of the membrane-associated 21-23 kDa substrates. Fractionation of the soluble extract from the cortex by Q-Sepharose anion exchange chromatography showed the presence of two distinct peaks of proteins presenting stimulating activities, eluting at 0.15 M (peak I) and 0.4 M (peak II) NaCl, respectively. Both peaks eluted as proteins of apparent molecular sizes of 40 kDa upon Superose 6 gel-filtration chromatography. No methylation activity towards N-acetyl-S-trans,trans-farnesylcysteine (AFC), a good substrate for C-terminal carboxyl methyltransferases, was associated with either peaks. In contrast, the increase in methylation induced by these proteins was strongly inhibited by AFC, suggesting that the methylation induced by these factors occurred on C-terminal isoprenylated cysteine residues. Both partially purified proteins competitively inhibited the methylation of AFC by the membrane-associated enzymes, suggesting that they may represent substrates for the methyltransferases. Immunoblotting of these partially purified soluble substrates with a rabbit polyclonal antibody directed against the small G-protein CDC42 showed the presence of this protein in peak I but not in peak II. Taken together, these results suggest the presence in a soluble fraction from the kidney of distinct methyl-accepting proteins, one of these being tentatively identified as the small G-protein CDC42.
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Affiliation(s)
- D Gingras
- Laboratoire de Membranologie, Université du Québec à Montréal, Canada
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13
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Pillinger M, Volker C, Stock J, Weissmann G, Philips M. Characterization of a plasma membrane-associated prenylcysteine-directed alpha carboxyl methyltransferase in human neutrophils. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)42282-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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14
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Sariban-Sohraby S, Fisher RS, Abramow M. Aldosterone-induced and GTP-stimulated methylation of a 90-kDa polypeptide in the apical membrane of A6 epithelia. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(19)74356-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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15
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Hrycyna CA, Clarke S. Modification of eukaryotic signaling proteins by C-terminal methylation reactions. Pharmacol Ther 1993; 59:281-300. [PMID: 8309992 DOI: 10.1016/0163-7258(93)90071-k] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Eukaryotic polypeptides that are initially synthesized with the C-terminal sequence -Cys-Xaa-Xaa-Xaa, including a variety of signal-transducing proteins, such as small G-proteins, large G-proteins and cGMP phosphodiesterases, can be targeted for a series of sequential post-translational modifications. This processing pathway includes the isoprenylation of the cysteine residue with a farnesyl or geranylgeranyl moiety, followed by proteolysis of the three terminal residues and alpha-carboxyl methyl esterification of the cysteine residue. The potential reversibility of the last step suggests that it may be involved in modulating the function of these proteins. Firstly, methylation may play a role in the activation of cellular peptides or proteins. Secondly, this modification may aid in the membrane attachment of cytosolic precursor proteins. Thirdly, methylation may protect the polypeptide from C-terminal proteolytic degradation once the three terminal amino acid residues are removed. Finally, reversible methylation may directly regulate the function of its target proteins. Therapeutically, inhibitors of C-terminal isoprenylcysteine methylation or demethylation reactions may prove to be useful pharmacological tools as anti-cancer and anti-inflammatory agents.
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Affiliation(s)
- C A Hrycyna
- Department of Chemistry and Biochemistry, University of California, Los Angeles 90024-1569
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16
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Kujubu DA, Stimmel JB, Law RE, Herschman HR, Clarke S. Early responses of PC-12 cells to NGF and EGF: effect of K252a and 5'-methylthioadenosine on gene expression and membrane protein methylation. J Neurosci Res 1993; 36:58-65. [PMID: 8230321 DOI: 10.1002/jnr.490360107] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Although epidermal growth factor (EGF) and nerve growth factor (NGF) have markedly different biological effects on PC-12 cells, many of the signaling events following ligand binding are similar. Both EGF and NGF result in the induction of the primary response gene egr-1/TIS8 and increased methylation of a variety of membrane-associated proteins as early as 5 min after EGF or NGF treatment using a methylation assay that detects methyl esters as well as methylated arginine residues. At 20 min after stimulation with these factors, the stimulation of methylation by NGF is greater than that of EGF, especially in the polypeptides of 36-42 and 20-22 kDa. To help dissect the pathways involved in these cellular responses, the protein kinase inhibitor K252a and the methyltransferase inhibitor 5'-methylthioadenosine (MTA) were used. Both K252a and MTA inhibit NGF-, but not EGF-mediated, primary response gene expression. In contrast, MTA, but not K252a, can block NGF-induced membrane associated protein methylation. These data suggest a role for differential protein methylation reactions in EGF and NGF signal transduction.
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Affiliation(s)
- D A Kujubu
- Department of Medicine, University of California, Los Angeles
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17
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Philips MR, Pillinger MH, Staud R, Volker C, Rosenfeld MG, Weissmann G, Stock JB. Carboxyl methylation of Ras-related proteins during signal transduction in neutrophils. Science 1993; 259:977-80. [PMID: 8438158 DOI: 10.1126/science.8438158] [Citation(s) in RCA: 176] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
In human neutrophils, as in other cell types, Ras-related guanosine triphosphate-binding proteins are directed toward their regulatory targets in membranes by a series of posttranslational modifications that include methyl esterification of a carboxyl-terminal prenylcysteine residue. In intact cells and in a reconstituted in vitro system, the amount of carboxyl methylation of Ras-related proteins increased in response to the chemoattractant N-formyl-methionyl-leucyl-phenylalanine (FMLP). Activation of Ras-related proteins by guanosine-5'-O-(3-thiotriphosphate) had a similar effect and induced translocation of p22rac2 from cytosol to plasma membrane. Inhibitors of prenylcysteine carboxyl methylation effectively blocked neutrophil responses to FMLP. These findings suggest a direct link between receptor-mediated signal transduction and the carboxyl methylation of Ras-related proteins.
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Affiliation(s)
- M R Philips
- Department of Medicine, New York University Medical Center, NY 10016
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18
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Backlund P. GTP-stimulated carboxyl methylation of a soluble form of the GTP-binding protein G25K in brain. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(19)36981-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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19
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Gingras D, Béliveau R. Guanine nucleotides stimulate carboxyl methylation of kidney cytosolic proteins. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1136:150-4. [PMID: 1504099 DOI: 10.1016/0167-4889(92)90250-f] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We studied the effect of guanine nucleotides on the carboxyl methylation catalyzed by class II protein carboxylmethyltransferases (PCMT). Addition of guanosine 5'-O-(gamma-thio)triphosphate (GTP gamma S) promoted a time- and concentration-dependent enhancement of protein methylation in the cytosolic fraction isolated from kidney cortex. GTP gamma S affected the kinetics of the methylation reaction, as reflected by alterations of both apparent Km and Vmax of the methyltransferase. This effect was specific for guanine nucleotides and was completely abolished by addition of S-adenosyl-L-homocysteine, a well-known inhibitor of methyltransferase-catalyzed reactions. No GTP gamma S stimulation of methylation was found in cytosolic extracts from any of the other tissues studied, including brain, testis, spleen, and liver, nor in brush-border membranes isolated from the kidney cortex. The methylated proteins were highly sensitive to moderately alkaline conditions, suggesting that the methyl esters were formed on L-isoaspartyl residues and thus methylated by a class II PCMT. These results suggest that class-II-associated protein methylation activity from the soluble fraction of the kidney can be regulated by guanine nucleotides.
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Affiliation(s)
- D Gingras
- Département de chimie-biochimie, Université du Québec à Montréal, Canada
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20
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Characterization of a rat liver protein carboxyl methyltransferase involved in the maturation of proteins with the -CXXX C-terminal sequence motif. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)42212-0] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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21
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Volker C, Miller R, McCleary W, Rao A, Poenie M, Backer J, Stock J. Effects of farnesylcysteine analogs on protein carboxyl methylation and signal transduction. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)54669-x] [Citation(s) in RCA: 81] [Impact Index Per Article: 2.5] [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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Solomon R, Ben Baruch G, Menczer J, Kloog Y. Downregulation of specific protein carboxylmethyltransferase immunoreactivity in human endometrial carcinoma. Cancer 1991; 68:1742-6. [PMID: 1913517 DOI: 10.1002/1097-0142(19911015)68:8<1742::aid-cncr2820680816>3.0.co;2-r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Protein carboxylmethyltransferases (PCMT), enzymes that methylate free carboxyl groups of proteins, are involved in functional modification of various proteins including those of age-damaged proteins and the oncogenic ras proteins. Several species of PCMT are associated with these modifications. By using western blot analysis and specific antibodies raised against one type of PCMT, a 30-kilodalton (KD) cytosolic enzyme from Torpedo electric organ was identified in human erythrocytes and endometrium. The high specificity of the antibodies made it possible to compare levels of immunoreactive 30-KD PCMT protein in normal human endometria and endometrial carcinomas. Assays done on samples from 23 patients indicated the average levels of immunoreactive 30-KD PCMT in endometrial carcinomas was one fifth that of normal endometrium. The sensitivity of the assay was 83%, and its specificity was 90%. These results suggest that levels and activity of the 30-KD PCMT may be downregulated to maintain the phenotypic expression of the endometrial carcinoma. These assays may be used to assist in the detection of endometrial carcinomas.
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Affiliation(s)
- R Solomon
- Department of Biochemistry, George S. Wise Faculty of Life Sciences, Tel Aviv University, Israel
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23
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Haklai R, Kloog Y. Relationship among methylation, isoprenylation, and GTP binding in 21- to 23-kDa proteins of neuroblastoma. Cell Mol Neurobiol 1991; 11:415-33. [PMID: 1751964 DOI: 10.1007/bf00711422] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
1. Dimethylsulfoxide-induced differentiated neuroblastoma express high levels of membrane 21 to 23-kDa carboxyl methylated proteins. Relationships among methylation, isoprenylation, and GTP binding in these proteins were investigated. Protein carboxyl methylation, protein isoprenylation, and [alpha-32P]GTP binding were determined in the electrophoretically separated proteins of cells labeled with the methylation precursor [methyl-3H]methionine or with an isoprenoid precursor [3H]mevalonate. 2. A broad band of GTP-binding proteins, which overlaps with the methylated 21 to 23-kDa proteins, was detected in [alpha-32P]GTP blot overlay assays. This band of proteins was separated in two-dimensional gels into nine methylated proteins, of which four bound GTP. 3. The carboxyl-methylated 21 to 23-kDa proteins incorporated [3H]mevalonate metabolites with characteristics of protein isoprenylation. The label was not removed by organic solvents or destroyed by hydroxylamine. Incorporation of radioactivity from [3H]mevalonate was enhanced when endogenous levels of mevalonate were reduced by lovastatin, an inhibitor of mevalonate synthesis. Lovastatin blocked methylation of the 21 to 23-kDa proteins as well (greater than 70%). 4. Methylthioadenosine, a methylation inhibitor, inhibited methylation of these proteins (greater than 80%) but did not affect their labeling by [3H]mevalonate. The results suggest that methylation of the 21 to 23-kDa proteins depends on, and is subsequent to, isoprenylation. The sequence of events may be similar to that known in ras proteins, i.e., carboxyl methylation of a C-terminal cysteine that is isoprenylated. 5. Lovastatin reduced the level of small GTP-binding proteins in the membranes and increased GTP binding in the cytosol. Methylthioadensoine blocked methylation without affecting GTP binding. 6. Thus, isoprenylation appears to precede methylation and to be important for membrane association, while methylation is not required for GTP binding or membrane association. The role of methylation remains to be determined but might be related to specific interactions of the small GTP-binding proteins with other proteins.
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Affiliation(s)
- R Haklai
- Department of Biochemistry, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Israel
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24
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Gingras D, Ménard P, Béliveau R. Protein carboxyl methylation in kidney brush-border membranes. BIOCHIMICA ET BIOPHYSICA ACTA 1991; 1066:261-7. [PMID: 1854790 DOI: 10.1016/0005-2736(91)90196-f] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Protein carboxyl methylation activity was detected in the cytosol and in purified brush-border membranes (BBM) from the kidney cortex. The protein carboxyl methyltransferase (PCMT) activity associated with the BBM was specific for endogenous membrane-bound protein substrates, while the cytosolic PCMT methylated exogenous substrates (ovalbumin and gelatin) as well as endogenous proteins. The apparent Km for S-adenosyl-L-methionine with endogenous proteins as substrates were 30 microM and 4 microM for the cytosolic and BBM enzymes, respectively. These activities were sensitive to S-adenosyl-L-homocysteine, a well known competitor of methyltransferase-catalyzed reactions, but were not affected by the presence of chymostatin and E-64, two protein methylesterase inhibitors. The activity of both cytosolic and BBM PCMT was maximal at pH 7.5, while BBM-phospholipid methylation was predominant at pH 10.0. Separation of the = methylated proteins by acidic gel electrophoresis in the presence of the cationic detergent benzyldimethyl-n-hexadecylammonium chloride revealed distinct methyl accepting proteins in the cytosol (14, 17, 21, 27, 31, 48, 61 and 168 kDa) and in the BBM (14, 60, 66, 82, and 105 kDa). Most of the labelling was lost following electrophoresis under moderately alkaline conditions, except for a 21 kDa protein in the cytosol and a 23 kDa protein in the BBM fraction. These results suggest the existence of two distinct PCMT in the kidney cortex: a cytosolic enzyme with low selectivity and affinity, methylating endogenous and exogenous protein substrates, and a high-affinity BBM-associated methylating activity.
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Affiliation(s)
- D Gingras
- Département de chimie-biochimie, Université du Québec à Montŕeal, Canada
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25
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Huzoor-Akbar, Winegar DA, Lapetina EG. Carboxyl methylation of platelet rap1 proteins is stimulated by guanosine 5'-(3-O-thio)triphosphate. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(20)64334-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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26
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Bourne HR, Sanders DA, McCormick F. The GTPase superfamily: a conserved switch for diverse cell functions. Nature 1990; 348:125-32. [PMID: 2122258 DOI: 10.1038/348125a0] [Citation(s) in RCA: 1803] [Impact Index Per Article: 53.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Proteins that bind and hydrolyse GTP are being discovered at a rapidly increasing rate. Each of these many GTPases acts as a molecular switch whose 'on' and 'off' states are triggered by binding and hydrolysis of GTP. Conserved structure and mechanism in myriad versions of the switch--in bacteria, yeast, flies and vertebrates--suggest that all derive from a single primordial protein, repeatedly modified in the course of evolution to perform a dazzling variety of functions.
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Affiliation(s)
- H R Bourne
- Department of Pharmacology, University of California, San Francisco 94143
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27
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Haklai R, Kloog Y. Methylation of 21-23 kD membrane proteins by a membrane-associated protein carboxyl methyltransferase in neuroblastoma cells. Increased methylation in differentiated cells. Biochem Pharmacol 1990; 40:1365-72. [PMID: 2403390 DOI: 10.1016/0006-2952(90)90405-a] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Membranes of neuroblastoma N1E-115 cells contain a specific protein carboxyl methyltransferase that methylates a 70 kD protein and a group of 21-23 kD proteins which are tightly bound to the membranes. The enzyme catalyzes the transfer of [methyl-3H] groups from [methyl-3H]S-adenosyl-L-methionine (Km = 0.22 microM) to these proteins to form base-labile carboxymethylesters. These protein methylesters are relatively stable compared to other protein methylesters, as shown by the ability of the 21-23 kD methylated proteins to retain their [methyl-3H] groups at pH values of 7 to 8.5 for at least 12 hr at room temperature. The extent of methylation of the 21-23 kD proteins, but not that of the 70 kD protein, was increased in membranes of cells induced to differentiate by 2% dimethyl sulfoxide (from a basal level of 0.1-0.2 to 0.9-1.2 pmol [methyl-3H] groups incorporated per mg membrane protein). This increase appeared after a lag period of 3 days of growth in the presence of the dimethyl sulfoxide and developed in parallel with the appearance of neurite-like processes in the cells. Kinetic experiments suggest that the amounts of 21-23 kD proteins available for methylation in the membranes of the undifferentiated and of the differentiated cells are limited. This and the previously observed low turnover of methylated 21-23 kD proteins in the intact cells suggest that the differentiated cells express and methylate more 21-23 kD proteins than the undifferentiated cells. These methylated proteins may be involved in differentiation or other functions of the differentiated cell membranes.
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Affiliation(s)
- R Haklai
- Department of Biochemistry, George S. Wise Faculty of Life Sciences, Tel Aviv University, Israel
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28
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Stephenson RC, Clarke S. Identification of a C-terminal protein carboxyl methyltransferase in rat liver membranes utilizing a synthetic farnesyl cysteine-containing peptide substrate. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(17)46215-6] [Citation(s) in RCA: 103] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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29
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Backlund P, Simonds W, Spiegel A. Carboxyl methylation and COOH-terminal processing of the brain G-protein gamma-subunit. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(18)55435-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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30
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Najbauer J, Aswad DW. Diversity of methyl acceptor proteins in rat pheochromocytoma (PC12) cells revealed after treatment with adenosine dialdehyde. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)38403-0] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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31
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Maltese WA, Sheridan KM, Repko EM, Erdman RA. Post-translational modification of low molecular mass GTP-binding proteins by isoprenoid. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)39953-3] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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32
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Haklai R, Kloog Y. Carboxyl methylation of 21-23 kDa membrane proteins in intact neuroblastoma cells is increased with differentiation. FEBS Lett 1990; 259:233-6. [PMID: 2294014 DOI: 10.1016/0014-5793(90)80016-c] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Evidence is presented for specific enzymatic methylation of 21-23 kDa membrane proteins in intact neuroblastoma N1E 115 cells, which is increased in dimethylsulfoxide-induced differentiated cells. Methylation of these proteins has characteristics typical of enzymatic reactions in which base labile volatile methyl groups are incorporated into proteins, consistent with the formation of protein carboxyl methylesters. However, these methylesters of the 21-23 kDa proteins are relatively stable compared to other protein carboxyl methylesters. The 3-fold increase in methylated 21-23 kDa proteins in the differentiated cells suggest biological significance in differentiation of the cell membranes.
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Affiliation(s)
- R Haklai
- Department of Biochemistry, George S. Wise Faculty of Life Sciences, Tel Aviv University, Israel
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33
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34
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Abstract
Protein carboxylmethyltransferase (PCM) is an enzyme whose function in eucaryotic cells remains controversial. Early studies suggested that protein carboxylmethylation subserved a regulatory, post-translational role in such diverse processes as secretion, neuronal receptor function, chemotaxis, and cellular differentiation. Later work strongly supported a totally unrelated role for this enzyme, i.e., the repair of spontaneously altered aspartate residues in cellular proteins. More recent evidence, however, suggests that a distinct, membrane-associated PCM catalyzes the methylation of alpha-carboxyl groups of C-terminal cysteines on discrete proteins. In view of these recent investigations, the data supporting a regulatory role for PCM are critically discussed and re-evaluated. There now appears to be compelling evidence that PCM(s) subserves both repair and regulatory functions in eucaryotic cells, catalyzing post-translational modifications of proteins involved in cell division, hormonal secretion, calmodulin-associated events and the interaction of guanyl nucleotide-linked proteins with the cell membrane.
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Affiliation(s)
- D M Barten
- Department of Pediatrics, University of Minnesota Medical School, Minneapolis
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35
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Affiliation(s)
- D W Aswad
- School of Biological Sciences, University of California, Irvine
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36
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Yamane HK, Fung BK. The membrane-binding domain of a 23-kDa G-protein is carboxyl methylated. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(19)47224-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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37
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Henzel WJ, Stults JT, Hsu CA, Aswad DW. The Primary Structure of a Protein Carboxyl Methyltransferase from Bovine Brain That Selectively Methylates L-Isoaspartyl Sites. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)71564-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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38
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Abstract
S-Adenosyl-L-methionine (AdoMet) is a safe and probably effective antidepressant agent in certain forms of clinical depression. This article presents a new hypothesis to account for the mechanism of action of S-adenosylmethionine in such illnesses, based upon the known biochemistry of this compound, and upon current knowledge of clinical and genetic aspects of affective disorders. Giulio Cantoni, S. Harvey Mudd and V. Andreoli postulate that at least some major mood disorders are due to abnormalities affecting the AdoMet-dependent methylation of a substance in the CNS. For convenience and without prejudging the chemical structure of this substance, they call it 'barinine'. The model requires that barinine be subject to AdoMet-dependent methylation and that methylbarinine be subject to metabolic demethylation to regenerate the original barinine. Methylbarinine should be mood elevating, whereas barinine itself should not be. Depression is a result of abnormalities lowering the normal steady-state concentration of methylbarinine, whereas mania results from an abnormal elevation of methylbarinine.
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39
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Ota IM, Clarke S. Enzymatic Methylation of 23-29-kDa Bovine Retinal Rod Outer Segment Membrane Proteins. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)51569-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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40
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41
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Chapter 25. Regulation of Neutrophil Chemotaxis. ANNUAL REPORTS IN MEDICINAL CHEMISTRY 1989. [DOI: 10.1016/s0065-7743(08)60547-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register]
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