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Vallesi A, Alimenti C, Federici S, Di Giuseppe G, Dini F, Guella G, Luporini P. Evidence for gene duplication and allelic codominance (not hierarchical dominance) at the mating-type locus of the ciliate, Euplotes crassus. J Eukaryot Microbiol 2014; 61:620-9. [PMID: 25040318 DOI: 10.1111/jeu.12140] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Revised: 03/25/2014] [Accepted: 05/03/2014] [Indexed: 11/30/2022]
Abstract
The high-multiple mating system of Euplotes crassus is known to be controlled by multiple alleles segregating at a single locus and manifesting relationships of hierarchical dominance, so that heterozygous cells would produce a single mating-type substance (pheromone). In strain L-2D, now known to be homozygous at the mating-type locus, we previously identified two pheromones (Ec-α and Ec-1) characterized by significant variations in their amino acid sequences and structure of their macronuclear coding genes. In this study, pheromones and macronuclear coding genes have been analyzed in strain POR-73 characterized by a heterozygous genotype and strong mating compatibility with L-2D strain. It was found that POR-73 cells contain three distinct pheromone coding genes and, accordingly, secrete three distinct pheromones. One pheromone revealed structural identity in amino acid sequence and macronuclear coding gene to the Ec-α pheromone of L-2D cells. The other two pheromones were shown to be new and were designated Ec-2 and Ec-3 to denote their structural homology with the Ec-1 pheromone of L-2D cells. We interpreted these results as evidence of a phenomenon of gene duplication at the E. crassus mating-type locus, and lack of hierarchical dominance in the expression of the macronuclear pheromone genes in cells with heterozygous genotypes.
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Affiliation(s)
- Adriana Vallesi
- Laboratory of Eukaryotic Microbiology and Animal Biology, University of Camerino, 62032, Camerino, MC, Italy
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2
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Cervia D, Catalani E, Belardinelli MC, Perrotta C, Picchietti S, Alimenti C, Casini G, Fausto AM, Vallesi A. The protein pheromone Er-1 of the ciliate Euplotes raikovi stimulates human T-cell activity: Involvement of interleukin-2 system. Exp Cell Res 2013; 319:56-67. [DOI: 10.1016/j.yexcr.2012.10.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Revised: 10/12/2012] [Accepted: 10/13/2012] [Indexed: 12/24/2022]
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3
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Alimenti C, Vallesi A, Luporini P, Buonanno F, Ortenzi C. Cell aging-induced methionine oxidation causes an autocrine to paracrine shift of the pheromone activity in the protozoan ciliate, Euplotes raikovi. Exp Cell Res 2012; 318:144-51. [DOI: 10.1016/j.yexcr.2011.10.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2011] [Revised: 10/13/2011] [Accepted: 10/14/2011] [Indexed: 01/10/2023]
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Alimenti C, Vallesi A, Federici S, di Giuseppe G, Fernando D, Carratore V, Luporini P. Isolation and structural characterization of two water-borne pheromones from Euplotes crassus, a ciliate commonly known to carry membrane-bound pheromones. J Eukaryot Microbiol 2011; 58:234-41. [PMID: 21414056 DOI: 10.1111/j.1550-7408.2011.00535.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Ciliates comprise species synthesizing water-diffusible mating type factors or pheromones and species synthesizing insoluble, cell membrane-bound pheromones. Euplotes crassus has traditionally been placed in the latter group. In contrast with this notion, we found that E. crassus is a constitutive pheromone-secreting ciliate, like other Euplotes species. From cell-free filtrate preparations of the E. crassus strain L-2D, we isolated two distinct pheromones, designated as Ec-α and Ec-1, and determined their complete amino acid sequences by combined chemical and genetic approaches. The Ec-α pheromone sequence extends for 56 amino acid residues with six cysteines and shows a molecular mass of 6,183 Da, while the Ec-1 pheromone sequence extends for 45 amino acid residues with 10 cysteines and shows a molecular mass of 4,840 Da. Marked structural differences distinguish the full-length Ec-α and Ec-1 coding sequences, which have been cloned and characterized from the transcriptionally active macronuclear genome. They were taken as clear indication that the Ec-α and Ec-1 pheromones are specified by genes that are not allelic, but likely derived from a duplicated genetic locus of the transcriptionally silent micronuclear genome.
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Affiliation(s)
- Claudio Alimenti
- Dipartimento di Scienze Ambientali e Naturali, University of Camerino, 62032 Camerino (MC), Italy
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5
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Ram JL, Müller CT, Beckmann M, Hardege JD. The spawning pheromone cysteine-glutathione disulfide ('nereithione') arouses a multicomponent nuptial behavior and electrophysiological activity in Nereis succinea males. FASEB J 1999; 13:945-52. [PMID: 10224237 DOI: 10.1096/fasebj.13.8.945] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The pheromone nereithione (cysteine-glutathione disulfide), which is released by swimming females of the polychaete Nereis succinea to activate spawning behavior of N. succinea males, has recently been identified and synthesized. Nereithione activates sperm release at less than 10(-6) M, one to two orders of magnitude less than oxidized glutathione or any other glutathione derivative tested. The glutathione fragment gamma-glu-cys inhibited sperm release. Nereithione aroused three components of the male nuptial behavior: circling, sperm release, and accelerated swimming. Electrophysiological activity elicited by nereithione near the sperm release site consisted of initial large spikes, cyclic bursting activity, and small spikes lasting up to a minute and was dose dependent, rapid, reversible, and repeatable. This preparation is an excellent model system for characterizing the receptors and functions of a marine pheromone.
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Affiliation(s)
- J L Ram
- Department of Physiology, Wayne State University, Detroit, Michigan 48201 USA.
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6
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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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7
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Luporini P, Miceli C, Ortenzi C, Vallesi A. Ciliate pheromones. PROGRESS IN MOLECULAR AND SUBCELLULAR BIOLOGY 1996; 17:80-104. [PMID: 8822801 DOI: 10.1007/978-3-642-80106-8_5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Affiliation(s)
- P Luporini
- Dipartimento di Biologia Molecolare, Cellulare e Animale, Università di Camerino, Italy
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8
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Ottiger M, Szyperski T, Luginbühl P, Ortenzi C, Luporini P, Bradshaw RA, Wüthrich K. The NMR solution structure of the pheromone Er-2 from the ciliated protozoan Euplotes raikovi. Protein Sci 1994; 3:1515-26. [PMID: 7833811 PMCID: PMC2142943 DOI: 10.1002/pro.5560030917] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The NMR structure of the pheromone Er-2 from the ciliated protozoan Euplotes raikovi has been determined in aqueous solution. The structure of this 40-residue protein was calculated with the distance geometry program DIANA from 621 distance constraints and 89 dihedral angle constraints; the program OPAL was employed for the energy minimization. For a group of 20 conformers used to characterize the solution structure, the average pairwise RMS deviation from the mean structure calculated for the backbone heavy atoms N, C alpha, and C' of residues 3-37 was 0.31 A. The molecular architecture is dominated by an up-down-up bundle of 3 short helices of residues 5-11, 14-20, and 23-33, which is similar to the structures of the homologous pheromones Er-1 and Er-10. Novel structural features include a well-defined N-cap on the first helix, a 1-residue deletion in the second helix resulting in the formation of a 3(10)-helix rather than an alpha-helix as found in Er-1 and Er-10, and the simultaneous presence of 2 different conformations for the C-terminal tetrapeptide segment, i.e., a major conformation with the Leu 39-Pro 40 peptide bond in the trans form and a minor conformation with this peptide bond in the cis form.
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Affiliation(s)
- M Ottiger
- Institut für Molekularbiologie und Biophysik, Eidgenössische Technische Hochschule, Zürich, Switzerland
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9
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Abstract
The ciliated protists (ciliates) offer a unique opportunity to explore the relationship between chemoreception and cell structure. Ciliates resemble chemosensory neurons in their responses to stimuli and presence of cilia. Ciliates have highly patterned surfaces that should permit precise localization of chemoreceptors in relation to effector organelles. Furthermore, ciliates are easy to grow and to manipulate genetically; they can also be readily studied biochemically and by electrophysiological techniques. This review contains a comparative description of the ultrastructural features of the ciliate cell surface relevant to chemoreception, examines the structural features of putative chemoreceptive cilia, and provides a summary of the electron microscopic information available so far bearing on chemoreceptive aspects of swimming, feeding, excretion, endocytosis, and sexual responses of ciliates. The electron microscopic identification and localization of specific chemoreceptive macromolecules and organelles at the molecular level have not yet been achieved in ciliates. These await the development of specific probes for chemoreceptor and transduction macromolecules. Nevertheless, the electron microscope has provided a wealth of information about the surface features of ciliates where chemoreception is believed to take place. Such morphological information will prove essential to a complete understanding of reception and transduction at the molecular level. In the ciliates, major questions to be answered relate to the apportionment of chemoreceptive functions between the cilia and cell soma, the global distribution of receptors in relation to the anterior-posterior, dorsal-ventral, and left-right axes of the cell, and the relationship of receptors to ultrastructural components of the cell coat, cell membrane, and cytoskeleton.
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Affiliation(s)
- L A Hufnagel
- Department of Microbiology, University of Rhode Island, Kingston 02881
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Stewart AE, Raffioni S, Chaudhary T, Chait BT, Luporini P, Bradshaw RA. The disulfide bond pairing of the pheromones Er-1 and Er-2 of the ciliated protozoan Euplotes raikovi. Protein Sci 1992; 1:777-85. [PMID: 1304918 PMCID: PMC2142243 DOI: 10.1002/pro.5560010609] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The disulfide pairings of the two Euplotes raikovi pheromones Er-1 and Er-2 have been determined by chemical and mass spectrometric analyses. Cystine-linked peptides from thermolytic digestions of the native molecules were purified by reverse-phase high performance liquid chromatography and identified in the known sequences to make the assignments. The same pairing, Cys(I)-Cys(IV), Cys(II)-Cys(VI), and Cys(III)-Cys(V), was found in both pheromones, suggesting that this pattern occurs commonly throughout this family of molecules. This arrangement of disulfides indicates that the three-dimensional structure is defined by three loops, which can vary in size and charge distribution from one pheromone to another.
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Affiliation(s)
- A E Stewart
- Department of Biological Chemistry, College of Medicine, University of California, Irvine 92717
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11
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Raffioni S, Miceli C, Vallesi A, Chowdhury SK, Chait BT, Luporini P, Bradshaw RA. Primary structure of Euplotes raikovi pheromones: comparison of five sequences of pheromones from cells with variable mating interactions. Proc Natl Acad Sci U S A 1992; 89:2071-5. [PMID: 1549567 PMCID: PMC48598 DOI: 10.1073/pnas.89.6.2071] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The amino acid sequences of five pheromones, Er-2, Er-3, Er-9, Er-11, and Er-20, secreted by cells of different mating types of the ciliated protozoa Euplotes raikovi, have been determined by automated Edman analyses of the whole proteins and germane fragments. In each case, the molecular mass was determined by plasma desorption or laser desorption mass spectrometry and was in excellent agreement with the calculated values. Where available, the determined sequences were also in accord with the corresponding segments of the precursor molecules predicted from relevant nucleic acid sequences. Of the five, two were found to be identical (Er-2 and Er-9) and one (Er-3) was identical to a pheromone previously sequenced (Er-1), even though mating pair formation was found to take place (although to a limited extent) when cells secreting those pheromones were combined in a mixture. Comparison of the five unique sequences suggested a closer relationship between Er-1 (Er-3) and Er-10 and between Er-11 and Er-20 (44% and 56% identity, respectively) than was generally observed among the other members. This pairing was also supported by hydrophobicity analyses. Interestingly, Er-20 cannot, as a rule, induce cell union in any of the other cell types, including cells secreting Er-11, despite the fact that Er-20 and Er-11 are the most similar of the five unique sequences. Thus sequence identity and secondary structure profiles are not a good indicator of biological relatedness as manifested in heterologous receptor interaction.
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Affiliation(s)
- S Raffioni
- Department of Biological Chemistry, College of Medicine, University of California, Irvine 92717
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12
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Miceli C, La Terza A, Bradshaw RA, Luporini P. Identification and structural characterization of a cDNA clone encoding a membrane-bound form of the polypeptide pheromone Er-1 in the ciliate protozoan Euplotes raikovi. Proc Natl Acad Sci U S A 1992; 89:1988-92. [PMID: 1542697 PMCID: PMC48579 DOI: 10.1073/pnas.89.5.1988] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
In the ciliate Euplotes raikovi, the same cell that secretes the pheromone Er-1, a polypeptide of 40 amino acids derived from a precursor (prepro-Er-1) of 75 amino acids, also produces a polypeptide of 130 amino acids, of which the 75 residues at the carboxyl terminus are identical to those of prepro-Er-1 and the 55 residues at the amino terminus form a new sequence. This larger Er-1 isoform is retained in membranes, where it may function as a binding site for soluble Er-1 in a mechanism of autocrine secretion. Membrane-bound and soluble Er-1 are translated from two mRNAs that apparently originate from a common micronuclear and/or macronuclear gene through alternative elimination of intervening sequences. This finding suggests that single genes responsible for the generation of isoform diversity in polypeptide hormones are present even in single-celled eukaryotes.
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Affiliation(s)
- C Miceli
- Department of Molecular, Cellular, and Animal Biology, University of Camerino, Italy
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Luporini P, Miceli C, Ortenzi C, Vallesi A. Developmental analysis of the cell recognition mechanism in the ciliate Euplotes raikovi. DEVELOPMENTAL GENETICS 1992; 13:9-15. [PMID: 1395147 DOI: 10.1002/dvg.1020130103] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Euplotes raikovi, like other ciliates, passes through a postconjugal immaturity, operatively identified by an apparent cell inability to form mating pairs under experimental conditions that are the same as those used for inducing mating at maturity. In cells homozygous for the gene mat-2, which controls the pheromone Er-2, Er-2 mRNA synthesis and mature Er-2 secretion were shown to start from the very beginning of the life cycle and continue throughout immaturity, although to extents estimated to be 5- to 10-fold lower than at maturity. In addition, experiments of 125I-Er-2 binding and crosslinking provided evidence that autocrine pheromone-binding sites, showing values of the dissociation constant of the order of 10(-9) M, are on the surface of immature cells. The number of these sites per cell was estimated to increase from less than 10(6) per cell of 5-7 fissions of age, to about 16 x 10(6) at maturity. These results were taken to suggest that a pheromone-receptor production is stimulated during immaturity by autocrine pheromone binding to cells and that this production might be essential for the development of a pheromone-receptor density high enough to transform the cell from "immature" to "adult," that is competent to respond as well to pheromones of conspecific, genetically different cells.
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Affiliation(s)
- P Luporini
- Department of Molecular, Cellular, and Animal Biology, University of Camerino, Italy
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14
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Anderson D, Raffioni S, Luporini P, Bradshaw RA, Eisenberg D. Crystallization of the Euplotes raikovi mating pheromone Er-1. J Mol Biol 1990; 216:1-2. [PMID: 2121998 DOI: 10.1016/s0022-2836(05)80055-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
A protein mating pheromone Er-1 from the ciliate Euplotes raikovi has been crystallized from (NH4)2SO4 in two forms. Both are suitable for structural studies to at least 2.8 A resolution. Both unit cell sizes are consistent with a tetramer of molecular weight 17,640 in the asymmetric unit.
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Affiliation(s)
- D Anderson
- Department of Chemistry and Biochemistry, University of California, Los Angeles 90024
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15
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Ortenzi C, Miceli C, Bradshaw RA, Luporini P. Identification and initial characterization of an autocrine pheromone receptor in the protozoan ciliate Euplotes raikovi. J Cell Biol 1990; 111:607-14. [PMID: 2166052 PMCID: PMC2116191 DOI: 10.1083/jcb.111.2.607] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The polypeptide pheromone Er-1, purified from the ciliate Euplotes raikovi of mating type I and genotype mat-1/mat-1, was iodinated with 125I-Bolton-Hunter reagent to a sp act of 0.45-0.73 mu Ci/microgram of protein. This preparation of 125I-Er-1 bound specifically to high affinity binding sites on the same cells of mating type I. Binding of 125I-Er-1 occurred with an apparent Kd of 4.63 +/- 0.12 X 10(-9) M in cells in early stationary phase. It was estimated that these cells carry a total number of approximately 5 X 10(7) sites/cell, with a site density that falls in the range of 1,600-1,700/microns 2 of cell surface. Unlabeled Er-1, other homologous pheromones such as Er-2 and Er-10, antibodies specific for Er-1, and human IL-2 were shown to act as effective inhibitors of specific binding of 125I-Er-1 to mating type I cells. The "autocrine" nature of the identified specific high affinity binding sites for Er-1 was further substantiated by cross-linking experiments. These experiments revealed that mating type-I cell membranes contain one protein entity of Mr = 28,000 that is capable of reacting specifically with the homodimeric native form of Er-1.
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Affiliation(s)
- C Ortenzi
- Department of Cell Biology, University of Camerino, Italy
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16
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Fiori PL, Miceli C, Raffioni S, Vallesi A. Specific and common epitopes in mating pheromones of Euplotes raikovi revealed by monoclonal antibodies. THE JOURNAL OF PROTOZOOLOGY 1990; 37:187-90. [PMID: 1694246 DOI: 10.1111/j.1550-7408.1990.tb01125.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Polypeptide mating pheromones Er-1 and Er-2, purified from the supernatant of Euplotes raikovi cultures of mating type I and mating type II, respectively, were used to immunize mice and obtain monoclonal antibodies. Five hybridoma clones producing antibodies specific to the mating pheromones were selected. They were analyzed for immunospecificity by immunoperoxidase assay, immunoblotting, and for their efficacy in inhibition of mating pheromone activity. Monoclonal antibodies from two hybridoma clones recognized only the mating pheromone used as antigen: those from the other three clones reacted, to comparable extents, with both mating pheromones. On the basis of these results it was assumed that two immunogenic sites exist in Er-1 and Er-2, one specific and the other common to both mating pheromones.
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Affiliation(s)
- P L Fiori
- Institute of Microbiology and Virology, University of Sassari, Italy
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17
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Miceli C, La Terza A, Melli M. Isolation and structural characterization of cDNA clones encoding the mating pheromone Er-1 secreted by the ciliate Euplotes raikovi. Proc Natl Acad Sci U S A 1989; 86:3016-20. [PMID: 2470086 PMCID: PMC287055 DOI: 10.1073/pnas.86.9.3016] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
cDNA clones comprising the entire coding region for the mating pheromone Er-1 of Euplotes raikovi have been isolated by oligonucleotide screening of two cDNA libraries in the vectors lambda gt10 and pUC12. The cDNA sequence contains an open reading frame of 75 amino acids that constitute pre-pro-Er-1. The amino acid sequence of secreted Er-1 starts at aspartic acid-36 of pre-pro-Er-1 and completely matches that known by direct Er-1 protein sequencing. The coding region of Er-1 cDNA ends with codon TAA, which specifies glutamine in other ciliates. The 5'- and 3'-noncoding regions contain, respectively, two and one inverted repeats. The 3'-noncoding-region inverted repeat, which includes the unusual polyadenylylation signal AACAAA, has been related to RNA 3'-terminus formation.
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Affiliation(s)
- C Miceli
- Department of Cell Biology, University of Camerino, Italy
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18
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Raffioni S, Luporini P, Chait BT, Disper SS, Bradshaw RA. Primary structure of the mating pheromone Er-1 of the ciliate Euplotes raikovi. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(19)81338-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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