Function of eukaryotic ribosomes

Bielka, H

doi:10.1007/978-3-642-68272-8_11

Cited by 15 publications

(22 citation statements)

References 660 publications

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“…Second, the RNA composition of P2 is also consistent with wheat germ ribosomal RNAs (Cammarano et al, 1972). Third, the protein composition of P2 falls in the range expected for wheat germ ribosomes (Bielka, 1982). Fourth, the weight ratio between RNA and protein content in P2 is also consistent with the reported data of ribosomes (Cammarano et al, 1972).…”

Section: Discussionsupporting

confidence: 82%

Role of Ribosomes in Reinitiation of Membrane Insertion of Internal Transmembrane Segments in a Polytopic Membrane Protein

et al. 1997

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The topogenesis of membrane proteins with a single transmembrane (TM) segment is well understood. However, understanding the topogenesis and membrane assembly of membrane proteins with multiple TM segments (polytopic) is still incomplete. Recently, several studies on P-glycoprotein (Pgp) suggested that the topogenesis of polytopic membrane proteins is likely more complicated than anticipated. While studying the mechanism by which Pgp topogenesis is determined, we unexpectedly found that ribosomes or proteins associated with ribosomes are involved in regulating the membrane insertion and folding of Pgp during its translation. We discovered that when Pgp was translated by wheat germ ribosomes in vitro, TM3 could not reinitiate the insertion of the protein into microsomal membranes following the membrane insertion of TM1 and TM2. In contrast, TM3 could reinitiate membrane insertion when the protein was translated by rabbit reticulocyte ribosomes. These findings suggest that ribosomes or proteins associated with ribosomes play an important role in membrane insertion and folding of TM segments of Pgp and that rabbit reticulocyte and wheat germ ribosomes may use different mechanisms to control the membrane insertion of the same nascent peptide. We propose that ribosomes or proteins associated with ribosomes help reinitiate insertion of internal TM segments into the membrane by dissociation and reassociation with the protein-conducting channel in ER membranes.

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Section: Discussionsupporting

confidence: 82%

Role of Ribosomes in Reinitiation of Membrane Insertion of Internal Transmembrane Segments in a Polytopic Membrane Protein

et al. 1997

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“…Gels were stained with 0.2% Coomassie brilliant blue G250 in 20% ethanoI/7% acetic acid, destained in the same mixture, dried under vacuum, and exposed to Kodak XAR-5 films at -80°C using intensifying screens. The protein band corre sponding to ribosomal protein S6 (Mr=31,000) [18] was cut out of the dried gel, and [,:!P] incorporation was quantitated by liquid scintilla tion spectroscopy.…”

Section: Sd S Polyacrylamide Gel Electrophoresismentioning

confidence: 99%

Ribosomal Protein S6 Kinase Is Activated after Folic Acid Injury and Epidermal Growth Factor Administration but Not after Unilateral Nephrectomy in the Rat Kidney

Alberti

Bardella²,

Comolli³

1992

Nephron

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Following loss of functional renal mass induced by a single parenteral injection of folic acid, the increased proliferation of tubular epithelium to replace injured and necrotic cells was associated with S6 kinase activation and enhanced phosphorylation of this ribosomal protein in vitro, EGF administered 1.5 h after folic acid promoted the phosphorylation of S6 protein and accelerated the regenerative repair process. In contrast, the hypertrophic response of the kidney following uninephrectomy was not associated with S6 kinase activation. The results of this study suggest a close correlation between levels of S6 protein phosphorylation and the degree of cell proliferation in the rat kidney.

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“…5). There was no inhibitory effect on the GTPase activity, and hence this suggests that the antibody did not inhibit the translocation of peptidyl-tRNA in the elongation cycle [24]. Nag et al [25] indicated that a monoclonal antibody to Escherichia coli 5 S-RNA-binding protein L5 inhibited the peptidyltransferase activity.…”

Section: Discussionmentioning

confidence: 99%

Effects of antibody to 5 S-RNA-binding protein on protein synthesis in Artemia salina ribosomes

Kenmochi

Takahashi

Sato

1989

Biochemical Journal

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The effects of an affinity-purified polyclonal antibody to Artemia salina ribosomal protein L5 on protein synthesis in vitro were examined. The antibody interacted with 60 S subunits more strongly than with 80 S ribosomes, and inhibited reassociation of ribosomal subunits to some extent at 5 mM-Mg2" but not at 10 mm. Polyphenylalanine synthesis in vitro at 10 mM-Mg2" was significantly inhibited, especially when the antibody was first preincubated with 60 S subunits prior to the assay. The incorporation of amino acid directed by globin mRNA was inhibited only when the preincubation with 60 S subunits was carried out. On the other hand, no effect was detected on elongation factor 2-and 60 S subunit-dependent uncoupled GTPase activity. These results suggest that L5 is probably located at or near the subunit interface and may play an important role in protein synthesis. INTRODUCTIONThe large ribosomal subunits of both prokaryotes and eukaryotes contain 5 S RNA, which is known to be a complex formed with one or more ribosomal proteins (for review, see ref. [1] [5][6][7] or other methods [8][9][10]. In rat liver, its protein moiety is identified as protein L5 [7]. One of us has shown that L5 crosslinked with poly(A)-containing mRNA in the polysome and to globin mRNA in the 80 S initiation complex following ultraviolet irradiation [11,12]. Furthermore, Uchiumi et al. [13] indicated that L5 crosslinked with small ribosomal subunit proteins S4 and S25 following treatment of 80 S ribosomes with 2-iminothiolane. These results suggest that rat liver L5 is probably located at the boundary between the large and small ribosomal subunits and interacts with mRNA.Recently, we identified the 5 S-RNA-binding protein of Artemia salina ribosomes, and showed immunological similarity between the proteins of Artemia and rat liver [14]. We therefore designated the protein as Artemia L5 (AL5) when compared with rat liver L5. In the present work, we used the affinity-purified antibody to AL5 and examined its effects on ribosomal functions in protein synthesis in vitro to elucidate the role of the 5 S-RNA-protein complex in ribosomes.

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Function of eukaryotic ribosomes

Cited by 15 publications

References 660 publications

Role of Ribosomes in Reinitiation of Membrane Insertion of Internal Transmembrane Segments in a Polytopic Membrane Protein

Role of Ribosomes in Reinitiation of Membrane Insertion of Internal Transmembrane Segments in a Polytopic Membrane Protein

Ribosomal Protein S6 Kinase Is Activated after Folic Acid Injury and Epidermal Growth Factor Administration but Not after Unilateral Nephrectomy in the Rat Kidney

Effects of antibody to 5 S-RNA-binding protein on protein synthesis in Artemia salina ribosomes

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