The largest known monomeric globular proteins

Reisner, A. H.; Rowe, Janet; Macindoe, Helen

doi:10.1016/0005-2795(69)90066-x

Cited by 34 publications

(12 citation statements)

References 17 publications

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“…The proteins have a Mr of 3()0,000, contain an unusually high number of disulfide bonds but little carbohydrate, and are acid stable and heat resistant. Each appears to be a single polypeptide (15)(16)(17). They show differences in their molecular weights, isoelectric points, and solubilities in ammonium sulfate and produce markedly different peptide maps.…”

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confidence: 99%

mRNAs for the immobilization antigens of Paramecium

Preer

Rudman

1981

Proc. Natl. Acad. Sci. U.S.A.

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Immobilization antigens of stock 51 of Paramecium tetraurelia were subjected to electrophoresis in NaDodSO4/ polyacrylamide gels. Type A is estimated to have a molecular size of 300,000 daltons; H is estimated to be 288,000, D to be 280,000, E to be 270,000, B to be 253,000, and C to be 250,000. Poly(A)+RNAs have been isolated from cells producing these antigens and subjected to electrophoresis in methylmercury gels. A major band is found to vary in mobility with antigenic type: Its position in preparations derived from paramecia synthesizing antigen A indicates a size of 8400 nucleotide residues; its position from paramecia synthesizing other antigens indicate H, 8200; D, 7900; E, 7500; B, 7600; and C, 7000. Because ofthe sizes and quantities of these RNAs, it is argued that they probably represent the mRNAs for the immobilization antigens. It is concluded that each immobilization antigen probably consists of a single polypeptide and that only one major serotype-determining mRNA is present in each antigenically different paramecium.Differences in gene expression that can be classified as simple environmental modifications are well known. Often, however, differences in gene expression show cellular inheritance; subclones that have alternative phenotypes may arise and reproduce true to type, even though all are under the same environmental conditions. The molecular mechanisms responsible for several instances ofinherited differences in gene expression have recently been discovered. Gene rearrangements have proved to be the basis for all cases. They include mating types in yeast (1), antigenic variation in Salmonella (2) and trypanosomes (3-5), and the production ofantibodies (6). Transposable elements in a variety of organisms (7-9) can also lead to modification of gene action.Since all ofthese cases involve changes in DNA, it is not surprising that they all are relatively stable and are not, as far as we know, directed by environmental stimuli. The production of antibodies may be an exception. Although antigens trigger the formation of specific antibodies, they do so by stimulating growth and synthesis. They select cells that have specific rearrangements, but there is no evidence that they induce rearrangements. Moreover, order in the sequence of changes exhibited by classes ofantibodies and in the succession ofantigenic types in trypanosomes does not necessarily imply specific induction. Nevertheless, a role for the environment in the induction of antibodies may exist, for the rearrangements occur in specific cells at specific times in development, suggesting that unknown inducing conditions may exist in those cells.Differences in the expression of genes determining immobilization proteins or i antigens (i-ags) of Paramecium are in some respects anomalous. They are heritable under certain environmental conditions and some show preferred sequences of change from one state to the other. Brown (10) has suggested that they too will prove to be due to gene rearrangments. However, they are unlike the cases d...

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confidence: 99%

mRNAs for the immobilization antigens of Paramecium

Preer

Rudman

1981

Proc. Natl. Acad. Sci. U.S.A.

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“…The analyses we describe above suggest that, while there are differences between the surface antigens isolated by Cross (-1975) from T. brucei when compared to those isolated from Paramecium (Jones, 1965;Reisner, Rowe and Macindoe, 1969;Reisner, Rowe and Sleigh, 1969), there are a number of important similarities, enough, we believe, to make Paramecium an important model system (Beale, 1974) to aid in understanding the relapse syndrome in trypanosomiasis (Vickerman, 1974). Firstly, there must be a number of amino acid residue differences between any two T. brucei surface proteins indicating that simple mutation cannot explain the relapse syndrome (serotypic transformation).…”

Section: Discussionmentioning

confidence: 91%

“…Firstly, there must be a number of amino acid residue differences between any two T. brucei surface proteins indicating that simple mutation cannot explain the relapse syndrome (serotypic transformation). Secondly, although the Paramecium surface proteins are four times the mass of those of T, brucei, both consist of single peptide chains (Cross, 1975;Reisner, Rowe and Macindoe, 1969;Hansma, 1975;Davis and Steers, 1976). This observation suggests that they are the end products of single structural genes.…”

Section: Discussionmentioning

confidence: 99%

DETERMINATION OF THE RELATEDNESS OF THE SOLUBLE SURFACE PROTEINS OF TRYPANOSOMA BRUCEI AND PARAMECIUM AURELIA

Reisner

Westwood

1977

Aust J Exp Biol Med

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Summary The soluble surface proteins isolated by Cross (1975) from Trypanosoma brucei are compared to those which occur on Paramecium aurelia. Calculations based on the amino acid residue data and the molecular weights of these surface antigens indicate that there is a considerable degree of similarity between the T. brucei and the P. aurelia proteins, and that in neither case can simple mutation be responsible for the differences of molecules within each family of antigens. The analyses are consistent with the suggestion that the P. aurelia system can serve as a model for the phenomenon of phase transformation (relapse syndrome) which occurs in trypanosomiasis.

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“…Paramecium surface proteins have molecular sizes ranging from 250 to 300 kDa. Each surface protein appears to consist of a single polypeptide chain (18,19,25,33,36). Trypanosoma briucei surface proteins have molecular sizes closer to those of T. thermophila (50 versus 58 kDa), but they lack disulfide bridges (6).…”

Section: Resultsmentioning

confidence: 99%

Structure and expression of two temperature-specific surface proteins in the ciliated protozoan Tetrahymena thermophila.

Bannon¹,

Perkins-Dameron²,

Allen-Nash³

1986

Mol. Cell. Biol.

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The presence of specific proteins (known as immobilization antigens) on the surface of the ciliated protozoan Tetrahymena thermophila is under environmental regulation. There are five different classes (serotypes) of surface proteins which appear on the cell surface when T. thermophila is cultured under different conditions of temperature or incubation medium; three of these are temperature dependent. The appearance of these proteins on the cell surface is mutually exclusive. We used polyclonal antibodies raised against 30°C (designated SerH3)-and 40°C (designated SerT)-specific surface antigens to study their structure and expression. We showed that these surface proteins contain at least one disulfide bridge. On sodium dodecyl sulfate-denaturing polyacrylamide gels, the nonreduced 30'C-and 40°C-specific surface proteins migrated with molecular sizes of 69 and 36 kilodaltons, respectively. The reduced forms of the proteins migrated with molecular sizes of 58 and 30 kilodaltons, respectively. The synthesis of the surface proteins responded rapidly and with a time course similar to that of the incubation temperature. The synthesis of each surface protein was greatly reduced within 1 h and undetectable by 2 h after a shift to the temperature at which the protein is not expressed. Surface protein synthesis resumed by the end of 1 h after a shift to the temperature at which the protein is expressed. The temperature-dependent induction of these surface proteins appears to be dependent on the synthesis of new mRNA, as indicated by a sensitivity to actinomycin D. Surface protein syntheses were mutually exclusive except at a transition temperature. At 35°C both surface proteins were synthesized by a cell population. These data support the potential of this system as a model for the study of the effects of environmental factors on the genetic regulation of cell surface proteins.Changes in gene expression in response to temperature shifts have been extensively documented. The heat shock response represents the major model system in eucaryotes in which environmental effects on gene regulation can be assessed. The heat shock response is ubiquitous in all organisms studied to date. It is manifested by the synthesis of 12 to 15 proteins whose expression can be brought about by a variety of environmental conditions (35). During the initial stages of a heat shock response, the synthesis of normal cell proteins is repressed. Depending on the organism, reexpression of normal cell proteins either can occur while the organism is still at the heat shock temperature or must wait until lower temperatures have been restored (17,20,23,26,27,34 between 20 and 35°C the protein designated SerH is on the cell surface (28). If this same population of cells is shifted to temperatures below 20°C the protein designated SerL is expressed, whereas if the cells are raised to 36 to 40°C the protein designated SerT appears on the surface (22, 30). The appearance of these proteins are mutually exclusive; that is, when one protein is on the surface, a...

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The largest known monomeric globular proteins

Cited by 34 publications

References 17 publications

mRNAs for the immobilization antigens of Paramecium

mRNAs for the immobilization antigens of Paramecium

DETERMINATION OF THE RELATEDNESS OF THE SOLUBLE SURFACE PROTEINS OF TRYPANOSOMA BRUCEI AND PARAMECIUM AURELIA

Structure and expression of two temperature-specific surface proteins in the ciliated protozoan Tetrahymena thermophila.

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