scholarly journals Gene expression in Acetabularia. II. Analysis of in vitro translation products

1982 ◽  
Vol 58 (1) ◽  
pp. 35-48
Author(s):  
R.L. Shoeman ◽  
H.G. Schweiger

The translation products induced by poly(A)+ RNA from Acetabularia mediterranea, A. cliftonii and A. ryukyuensis in a modified, highly efficient wheat germ cell-free in vitro system were separated by two-dimensional gel electrophoresis. A comparison of the translation products on the basis of their molecular weight and their isoelectric point revealed only a limited similarity between the patterns of the three species. The pronounced species specificity will permit the study of the in vivo translation of heterologous poly(A)+ RNA in Acetabularia cytoplasm.

Development ◽  
1985 ◽  
Vol 89 (1) ◽  
pp. 275-287
Author(s):  
William R. Jeffery

The yellow crescent or myoplasm is a localized cytoplasmic region in eggs of the ascidian Styela that is partitioned to the larval tail muscle and mesenchyme cells during embryonic development. To determine whether the myoplasm contains a specific subset of maternal macromolecules, its abundant proteins and mRNAs were identified and compared to those present in the remainder of the egg. This was accomplished by exploiting a newly developed method for the mass fractionation of yellow crescents which is based on the presence of a unique cytoskeletal domain in the yellow crescent region. The fractionation yields a yellow crescent fraction (YCF) representing the myoplasm and a supernatant fraction representing the nonmyoplasmic regions. The YCF comprises structures which contain the characteristic myoplasmic organelles and about 10% of the protein, 8% of the RNA, and 1–3% of the poly (A) of whole eggs. Two-dimensional gel electrophoresis indicated that the YCF contains 15 polypeptides that are undetectable in the supernatant fraction and 43 polypeptides that are significantly depleted in the latter fraction. The proteins restricted to the YCF are both of cytoskeletal and noncytoskeletal origin. In vitro translation of RNA in a message-dependent lysate and analysis of [35S]methionine-labelled polypeptide products by two-dimensional gel electrophoresis did not reveal qualitative differences between the YCF and the supernatant fraction. Furthermore, the mRNAs coding for two polypeptides that were localized in the myoplasm were not restricted to the YCF. The results suggest that qualitative differences in proteins but not in prevalent mRNAs exist between the yellow crescent and the other cytoplasmic regions of Styela eggs.


1985 ◽  
Vol 63 (7) ◽  
pp. 705-710 ◽  
Author(s):  
Pierre Chapdelaine ◽  
Jean Y. Dubé ◽  
Gilles Frenette ◽  
Roland R. Tremblay

Poly(A)+ rich RNA was isolated from prostate of adult dogs and translated in the rabbit reticulocyte lysate cell-free protein-synthesizing system. Two-dimensional gel electrophoresis of the translation products showed that a protein with a molecular weight of 31 000 was predominantly synthesized. This protein was immunoprecipitated with antibodies directed against purified arginine esterase from dog seminal plasma. mRNA isolated from the prostate of animals castrated for 1 or 2 weeks was unable to direct the synthesis of arginine esterase. However, the synthesis of the enzyme could be stimulated by androgens in castrated animals, presumably by increasing prostatic concentrations of arginine esterase mRNA. The single chain translation product could be further processed in vitro by the addition of dog pancreas microsomes and purified arginine esterase. This procedure yielded split chains of arginine esterase which had identical electrophoretic mobilities as seminal plasma enzyme by two-dimensional gel electrophoresis. When prostatic tissue slices were incubated with tunicamycin, the unglycosylated arginine esterase obtained had a lower molecular weight than the in vitro translation product, suggesting that a signal peptide had been removed in the living cells. These results indicate that arginine esterase processing may include the following steps: removal of a signal peptide, glycosylation, and splitting of the polypeptide chain by active arginine esterase in the secretory granules or outside the cell.


Biology ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1195
Author(s):  
Jorge Cebrián ◽  
Victor Martínez ◽  
Pablo Hernández ◽  
Dora B. Krimer ◽  
María-José Fernández-Nestosa ◽  
...  

DNA topoisomerases are the enzymes that regulate DNA topology in all living cells. Since the discovery and purification of ω (omega), when the first were topoisomerase identified, the function of many topoisomerases has been examined. However, their ability to relax supercoiling and unlink the pre-catenanes of partially replicated molecules has received little attention. Here, we used two-dimensional agarose gel electrophoresis to test the function of three type II DNA topoisomerases in vitro: the prokaryotic DNA gyrase, topoisomerase IV and the human topoisomerase 2α. We examined the proficiency of these topoisomerases on a partially replicated bacterial plasmid: pBR-TerE@AatII, with an unidirectional replicating fork, stalled when approximately half of the plasmid had been replicated in vivo. DNA was isolated from two strains of Escherichia coli: DH5αF’ and parE10. These experiments allowed us to assess, for the first time, the efficiency of the topoisomerases examined to resolve supercoiling and pre-catenanes in partially replicated molecules and fully replicated catenanes formed in vivo. The results obtained revealed the preferential functions and also some redundancy in the abilities of these DNA topoisomerases in vitro.


1985 ◽  
Vol 5 (3) ◽  
pp. 586-590
Author(s):  
A M Francoeur ◽  
E K Chan ◽  
J I Garrels ◽  
M B Mathews

HeLa cell La antigen, an RNA-binding protein, was characterized by using two-dimensional gel electrophoresis. Eight isoelectric forms (pI 6 to 7) were observed, many containing phosphate. An in vitro translation product similar in size and antigenicity was identified. The HeLa cell protein purified by using an assay based on ribonucleoprotein reconstitution with adenovirus VA RNAI also comprised several isoelectric forms.


1981 ◽  
Vol 91 (2) ◽  
pp. 352-360 ◽  
Author(s):  
TW McKeithan ◽  
JL Rosenbaum

The alga polytomella contains several organelles composed of microtubules, including four flagella and hundreds of cytoskeletal microtubules. Brown and co-workers have shown (1976. J. Cell Biol. 69:6-125; 1978, Exp. Cell Res. 117: 313-324) that the flagella could be removed and the cytoskeletans dissociated, and that both structures could partially regenerate in the absence of protein synthesis. Because of this, and because both the flagella and the cytoskeletons can be isolated intact, this organism is particularly suitable for studying tubulin heterogeneity and the incorporation of specific tubulins into different microtubule-containing organelles in the same cell. In order to define the different species of tubulin in polytonella cytoplasm, a (35)S- labeled cytoplasmic fraction was subjected to two cycles of assembly and disassembly in the presence of unlabeled brain tubulin. Comparison of the labeled polytomella cytoplasmic tubulin obtained by this procedure with the tubulin of isolated polytomella flagella by two-dimensional gel electrophoresis showed that, whereas the β-tubulin from both cytoplasmic and flagellar tubulin samples comigrated, the two α-tubulins had distinctly different isoelectic points. As a second method of isolating tubulin from the cytoplasm, cells were gently lysed with detergent and intact cytoskeletons obtained. When these cytoskeletons were exposed to cold temperature, the proteins that were released were found to be highly enriched in tubulin; this tubulin, by itself, could be assembled into microtubules in vitro. The predominant α-tubulin of this in vitro- assembled cytoskeletal tubulin corresponded to the major cytoplasmic α-tubulin obtained by coassembly of labeled polytomella cytoplasmic extract with brain tubulin and was quite distinct from the α-tubulin of purified flagella. These results clearly show that two different microtubule-containing organelles from the same cell are composed of distinct tubulins.


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