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Genome-Wide Identification of G Protein-Coupled Receptors in Ciliated Eukaryotes. Int J Mol Sci 2023; 24:ijms24043869. [PMID: 36835283 PMCID: PMC9960496 DOI: 10.3390/ijms24043869] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 02/07/2023] [Accepted: 02/12/2023] [Indexed: 02/17/2023] Open
Abstract
G protein-coupled receptors (GPCRs) are the largest family of transmembrane receptors and play important roles in many physiological processes. As a representative group of protozoa, ciliates represent the highest stage of eukaryotic cell differentiation and evolution in terms of their reproductive mode, two-state karyotype, and extremely diverse cytogenesis patterns. GPCRs have been poorly reported in ciliates. In this study, we identified 492 GPCRs in 24 ciliates. Using the existing classification system for animals, GPCRs in ciliates can be assigned to four families, including families A, B, E, and F. Most (377 members) belong to family A. The number of GPCRs is extremely different in different ciliates; the Heterotrichea ciliates usually have more GPCRs than other ciliates. Parasitic or symbiotic ciliates usually have only a few GPCRs. Gene/genome duplication events seem to play important roles in the expansion of the GPCR superfamily in ciliates. GPCRs in ciliates displayed seven typical domain organizations. GPCRs in an ortholog group are common and conserved in all ciliates. The gene expression analysis of the members in this conserved ortholog group in the model ciliate, Tetrahymena thermophila, suggested that these GPCRs play important roles in the life cycle of ciliates. In summary, this study provides the first comprehensive genome-wide identification of GPCRs in ciliates, improving our understanding of the evolution and function of GPCR in ciliates.
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Abstract
All living cells interact dynamically with a constantly changing world. Eukaryotes, in particular, evolved radically new ways to sense and react to their environment. These advances enabled new and more complex forms of cellular behaviour in eukaryotes, including directional movement, active feeding, mating, and responses to predation. But what are the key events and innovations during eukaryogenesis that made all of this possible? Here we describe the ancestral repertoire of eukaryotic excitability and discuss five major cellular innovations that enabled its evolutionary origin. The innovations include a vastly expanded repertoire of ion channels, the emergence of cilia and pseudopodia, endomembranes as intracellular capacitors, a flexible plasma membrane and the relocation of chemiosmotic ATP synthesis to mitochondria, which liberated the plasma membrane for more complex electrical signalling involved in sensing and reacting. We conjecture that together with an increase in cell size, these new forms of excitability greatly amplified the degrees of freedom associated with cellular responses, allowing eukaryotes to vastly outperform prokaryotes in terms of both speed and accuracy. This comprehensive new perspective on the evolution of excitability enriches our view of eukaryogenesis and emphasizes behaviour and sensing as major contributors to the success of eukaryotes. This article is part of the theme issue 'Basal cognition: conceptual tools and the view from the single cell'.
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Affiliation(s)
- Kirsty Y. Wan
- Living Systems Institute, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
| | - Gáspár Jékely
- Living Systems Institute, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
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Lampert TJ, Coleman KD, Hennessey TM. A knockout mutation of a constitutive GPCR in Tetrahymena decreases both G-protein activity and chemoattraction. PLoS One 2011; 6:e28022. [PMID: 22140501 PMCID: PMC3226668 DOI: 10.1371/journal.pone.0028022] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Accepted: 10/30/2011] [Indexed: 11/18/2022] Open
Abstract
Although G-protein coupled receptors (GPCRs) are a common element in many chemosensory transduction pathways in eukaryotic cells, no GPCR or regulated G-protein activity has yet been shown in any ciliate. To study the possible role for a GPCR in the chemoresponses of the ciliate Tetrahymena, we have generated a number of macronuclear gene knockouts of putative GPCRs found in the Tetrahymena Genome database. One of these knockout mutants, called G6, is a complete knockout of a gene that we call GPCR6 (TTHERM_00925490). Based on sequence comparisons, the Gpcr6p protein belongs to the Rhodopsin Family of GPCRs. Notably, Gpcr6p shares highest amino acid sequence homologies to GPCRs from Paramecium and several plants. One of the phenotypes of the G6 mutant is a decreased responsiveness to the depolarizing ions Ba2+ and K+, suggesting a decrease in basal excitability (decrease in Ca2+ channel activity). The other major phenotype of G6 is a loss of chemoattraction to lysophosphatidic acid (LPA) and proteose peptone (PP), two known chemoattractants in Tetrahymena. Using microsomal [35S]GTPγS binding assays, we found that wild-type (CU427) have a prominent basal G-protein activity. This activity is decreased to the same level by pertussis toxin (a G-protein inhibitor), addition of chemoattractants, or the G6 mutant. Since the basal G-protein activity is decreased by the GPCR6 knockout, it is likely that this gene codes for a constitutively active GPCR in Tetrahymena. We propose that chemoattractants like LPA and PP cause attraction in Tetrahymena by decreasing the basal G-protein stimulating activity of Gpcr6p. This leads to decreased excitability in wild-type and longer runs of smooth forward swimming (less interrupted by direction changes) towards the attractant. Therefore, these attractants may work as inverse agonists through the constitutively active Gpcr6p coupled to a pertussis-sensitive G-protein.
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Affiliation(s)
- Thomas J Lampert
- Department of Biological Sciences, University at Buffalo, Amherst, New York, United States of America
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Chemoattraction to lysophosphatidic acid does not require a change in membrane potential inTetrahymena thermophila. Cell Biol Int 2011; 35:519-28. [DOI: 10.1042/cbi20100320] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Chaine AS, Schtickzelle N, Polard T, Huet M, Clobert J. Kin-based recognition and social aggregation in a ciliate. Evolution 2009; 64:1290-300. [PMID: 19930455 DOI: 10.1111/j.1558-5646.2009.00902.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Aggregative groups entail costs that must be overcome for the evolution of complex social interactions. Understanding the mechanisms that allow aggregations to form and restrict costs of cheating can provide a resolution to the instability of social evolution. Aggregation in Tetrahymena thermophila is associated with costs of reduced growth and benefits of improved survival through "growth factor" exchange. We investigated what mechanisms contribute to stable cooperative aggregation in the face of potential exploitation by less-cooperative lines using experimental microcosms. We found that kin recognition modulates aggregative behavior to exclude cheaters from social interactions. Long-distance kin recognition across patches modulates social structure by allowing recruitment of kin in aggregative lines and repulsion in asocial lines. Although previous studies have shown a clear benefit to social aggregation at low population densities, we found that social aggregation has very different effects at higher densities. Lower growth rates are a cost of aggregation, but also present potential benefits when restricted to kin aggregations: slow growth and crowd tolerance allow aggregations to form and permit longer persistence on ephemeral resources. Thus in highly dynamic metapopulations, kin recognition plays an important role in the formation and stability of social groups that increase persistence through cooperative consumptive restraint.
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Affiliation(s)
- Alexis S Chaine
- Station d'Ecologie Expérimentale du CNRS à Moulis USR2936, 09200 Saint-Girons, France.
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6
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Govorunova EG, Sineshchekov OA. Chemotaxis in the green flagellate alga Chlamydomonas. BIOCHEMISTRY (MOSCOW) 2006; 70:717-25. [PMID: 16097934 DOI: 10.1007/s10541-005-0176-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Behavior of the green flagellate alga Chlamydomonas changes in response to a number of chemical stimuli. Specific sensitivity of the cells to different substances might appear only at certain stages of the life cycle. The heterogamous species C. allensworthii demonstrates chemotaxis of male gametes towards pheromones excreted by female gametes. In C. reinhardtii chemotaxis towards tryptone occurs only in gametes, whereas chemotaxis towards ammonium, on the contrary, only in vegetative cells. Chemotaxis to different chemical stimuli might involve different mechanisms of reception and signal transduction, elucidation of which has only recently begun. Indirect evidences show that the cells likely respond to tryptone with changes in the membrane electrical conductance. The recently completed project of sequencing the whole nuclear genome of C. reinhardtii provides the basis for future identification of molecular elements of the chemosensory cascade in this alga.
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Affiliation(s)
- E G Govorunova
- Faculty of Biology, Lomonosov Moscow State University, Moscow, 119992, Russia.
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Chen F, Leick V. The protozoan Tetrahymena as a bioindicator to screen bioactive substances. J Microbiol Methods 2004; 59:233-41. [PMID: 15369859 DOI: 10.1016/j.mimet.2004.07.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2004] [Accepted: 07/12/2004] [Indexed: 11/19/2022]
Abstract
Tetrahymena thermophila has been used as a "swimming receptor" to study its chemotaxis in the presence of various bioactive substances from herbal plants. Chemotaxis of this ciliated protozoan is, in part, controlled by a cyclic GMP-dependent protein kinase (PKG), which can adjust ciliary beating. In this paper, the effects of Ginkgo biloba extract (GBE) and its main functional constituents, terpene lactones, flavonol glycosides and aglycones, on the chemotaxis and PKG activity of ciliates, were systematically investigated. GBE and its constituents exerted significant inhibition of chemotaxis and PKG activity in cells of T. thermophila. The minimal concentrations to completely inhibit chemotaxis of T. thermophila were 12, 25, 50, 100, 300, 400, 400, 500 microM, 2 mg/ml for isorhamnetin, kaempferol, quercetin, myricetin, isoquercitrin, quercetin-3-beta-d-galactoside, rutin, quercitrin, and GBE, respectively. The IC(50) values for PKG were 14, 17, 20, 25, 186, 78 microM, 0.157 mg/ml for isorhamnetin, kaempferol, quercetin, myricetin, isoquercitrin, rutin and GBE, respectively. The results indicate that the chemotaxis inhibition by GBE and its constituents and their effects on PKG are similar. This suggests that T. thermophila may be a potential experimental organism for screening other bioactive substances.
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Affiliation(s)
- Fusheng Chen
- Food Science and Technology College, Huazhong Agricultural University, Wuhan 430070, Hubei Province, P.R. China.
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Paramá A, Iglesias R, Alvarez MF, Sanmartín ML, Leiro J. Chemotactic responses of the fish-parasitic scuticociliate Philasterides dicentrarchi to blood and blood components of the turbot Scophthalmus maximus, evaluated using a new microplate multiassay. J Microbiol Methods 2004; 58:361-6. [PMID: 15279940 DOI: 10.1016/j.mimet.2004.04.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2004] [Revised: 03/11/2004] [Accepted: 04/28/2004] [Indexed: 11/22/2022]
Abstract
This study describes a new capillary-type microplate multiassay for characterization of protozoal chemotactic responses, allowing up to 32 assays to be run simultaneously. We used the new multiassay to evaluate the chemoattractant activity of turbot blood components and turbot cells for the facultative parasite Philasterides dicentrarchi, which is responsible for significant losses in turbot farming. Preliminary tests indicated that the assay requires 3-4 h for detection of chemoattractant activity, that it can be performed effectively using the ciliate axenic culture medium, and that it distinguishes clearly between different concentrations of chemoattractant. Application of the assay indicated that whole blood and serum from normal turbot, and especially infected turbot, have strong chemoattractant activity for P. dicentrarchi trophozoites, whereas neither turbot blood cells nor other turbot cells nor bacteria were significant chemoattractants. These results raise the possibility that turbot serum components are involved in host detection and host invasion by P. dicentrarchi, in line with previous findings indicating that turbot with skin lesions show increased susceptibility to P. dicentrarchi infection.
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Affiliation(s)
- A Paramá
- Laboratorio de Parasitología, Instituto de Investigación y Análisis Alimentarios, Universidad de Santiago de Compostela, C/ Constantino Candeira, s/n, Santiago de Compostela 15782, Spain
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Wilks SA, Sleigh MA. Lectin binding sites on Euplotes mutabilis (Tuffrau, 1960) and the implications for food particle selection. Eur J Protistol 2004. [DOI: 10.1016/j.ejop.2004.01.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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10
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Guerra C, Wada Y, Leick V, Bell A, Satir P. Cloning, localization, and axonemal function of Tetrahymena centrin. Mol Biol Cell 2003; 14:251-61. [PMID: 12529441 PMCID: PMC140242 DOI: 10.1091/mbc.e02-05-0298] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Centrin, an EF hand Ca(2+) binding protein, has been cloned in Tetrahymena thermophila. It is a 167 amino acid protein of 19.4 kDa with a unique N-terminal region, coded by a single gene containing an 85-base pair intron. It has > 80% homology to other centrins and high homology to Tetrahymena EF hand proteins calmodulin, TCBP23, and TCBP25. Specific cellular localizations of the closely related Tetrahymena EF hand proteins are different from centrin. Centrin is localized to basal bodies, cortical fibers in oral apparatus and ciliary rootlets, the apical filament ring and to inner arm (14S) dynein (IAD) along the ciliary axoneme. The function of centrin in Ca(2+) control of IAD activity was explored using in vitro microtubule (MT) motility assays. Ca(2+) or the Ca(2+)-mimicking peptide CALP1, which binds EF hand proteins in the absence of Ca(2+), increased MT sliding velocity. Antibodies to centrin abrogated this increase. This is the first demonstration of a specific centrin function associated with axonemal dynein. It suggests that centrin is a key regulatory protein for Tetrahymena axonemal Ca(2+) responses, including ciliary reversal or chemotaxis.
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Affiliation(s)
- Charles Guerra
- Department of Anatomy and Structural Biology, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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11
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Origins of Signalling and Memory: Matters of Life Versus Death. ACTA BIOLOGICA HUNGARICA 1999. [DOI: 10.1007/bf03543064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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12
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Chapter 17 Electrophysiology of Tetrahymena. Methods Cell Biol 1999. [DOI: 10.1016/s0091-679x(08)61543-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
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13
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Christensen ST, Leick V, Rasmussen L, Wheatley DN. Signaling in unicellular eukaryotes. INTERNATIONAL REVIEW OF CYTOLOGY 1997; 177:181-253. [PMID: 9378617 DOI: 10.1016/s0074-7696(08)62233-0] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Aspects of intercellular and intracellular signaling systems in cell survival, proliferation, differentiation, chemosensory behavior, and programmed cell death in free-living unicellular eukaryotes have been reviewed. Comparisons have been made with both bacteria and metazoa. The central organisms were flagellates (Trypanosoma, Leishmania, and Crithidia), slime molds (Dictyostelium), yeast cells (Saccharomyces cerevisiae), and ciliates (Paramecium, Euplotes, and Tetrahymena). There are two novel aspects in this review. First, cellular responses are viewed in an evolutionary perspective, rather than from the more prevailing one, in which the unicellular eukaryotes are seen by the mammalian organisms. Second, results obtained with cell cultures in minimal, chemically defined nutrient media at low cell densities where intercellular signaling is strongly reduced are discussed. These results shed light on control mechanisms and their cooperation inside the living cell. Intracellular systems have many common features in unicellular and multicellular organisms.
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Affiliation(s)
- S T Christensen
- Department of Medical Biochemistry and Genetics, Panum Institute, University of Copenhagen, Denmark
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KURUVILLA HEATHERG, KIM MARKY, HENNESSEY TODDM. Chemosensory Adaptation to Lysozyme and GTP Involves Independently Regulated Receptors in Tetrahymena thermophila. J Eukaryot Microbiol 1997. [DOI: 10.1111/j.1550-7408.1997.tb05710.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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15
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Kuyper LF, Baccanari DP, Jones ML, Hunter RN, Tansik RL, Joyner SS, Boytos CM, Rudolph SK, Knick V, Wilson HR, Caddell JM, Friedman HS, Comley JC, Stables JN. High-affinity inhibitors of dihydrofolate reductase: antimicrobial and anticancer activities of 7,8-dialkyl-1,3-diaminopyrrolo[3,2-f]quinazolines with small molecular size. J Med Chem 1996; 39:892-903. [PMID: 8632413 DOI: 10.1021/jm9505122] [Citation(s) in RCA: 80] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
A series of 7,8-dialkylpyrrolo[3,2-f]quinazolines were prepared as inhibitors of dihydrofolate reductase (DHFR). On the basis of an apparent inverse relationship between compound size and antifungal activity, the compounds were designed to be relatively small and compact. Inhibitor design was aided by GRID analysis of the three-dimensional structure of Candida albicans DHFR, which suggested that relatively small, branched alkyl groups at the 7- and 8-positions of the pyrroloquinazoline ring system would provide optimal interactions with a hydrophobic region of the protein. The compounds were potent inhibitors of fungal and human DHFR, with K(i) values as low as 7.1 and 0.1 pM, respectively, and were highly active against C. albicans and an array of tumor cell lines. In contrast to known lipophilic inhibitors of DHFR such as trimetrexate and piritrexim, members of this series of pyrroloquinazolines were not susceptible to P-glycoprotein-mediated multidrug resistance and also showed significant distribution into lung and brain tissue. The compounds were active in lung and brain tumor models and displayed in vivo activity against Pneumocystis carinii and C. albicans.
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MESH Headings
- ATP Binding Cassette Transporter, Subfamily B, Member 1/drug effects
- Animals
- Anti-Infective Agents/chemical synthesis
- Anti-Infective Agents/pharmacology
- Anti-Infective Agents/toxicity
- Antineoplastic Agents/chemical synthesis
- Antineoplastic Agents/pharmacology
- Antineoplastic Agents/toxicity
- Brain Neoplasms/drug therapy
- Candidiasis/drug therapy
- Cell Division/drug effects
- Cell Line
- Crystallography, X-Ray
- Drug Design
- Drug Resistance, Multiple
- Enzyme Inhibitors/chemical synthesis
- Enzyme Inhibitors/pharmacology
- Folic Acid Antagonists/chemistry
- Humans
- Lung Neoplasms/drug therapy
- Magnetic Resonance Spectroscopy
- Mass Spectrometry
- Mice
- Mice, Nude
- Mice, SCID
- Models, Molecular
- Molecular Conformation
- Molecular Structure
- Molecular Weight
- Pneumonia, Pneumocystis/drug therapy
- Protein Structure, Secondary
- Quinazolines/chemical synthesis
- Quinazolines/pharmacology
- Quinazolines/toxicity
- Structure-Activity Relationship
- Toxoplasma/drug effects
- Tumor Cells, Cultured
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Affiliation(s)
- L F Kuyper
- Wellcome Research Laboratories, Research Triangle Park, North Carolina 27709, USA
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Leick V, Grave M, Hellung-Larsen P. Signal peptide-induced sensory behavior in free ciliates: bioassays and cellular mechanisms. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 1996; 17:61-79. [PMID: 8822800 DOI: 10.1007/978-3-642-80106-8_4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- V Leick
- Department of Biochemistry B, University of Copenhagen, Denmark
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