Dissociation and reassociation of skeletal muscle ribosomes

Martin, Terence E.; Rolleston, Francis S.; Low, Robert B.; Wool, Ira G.

doi:10.1016/0022-2836(69)90084-9

Cited by 156 publications

(31 citation statements)

References 15 publications

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“…The selection of 0.40 M KCl concentration compared to the 0.60 M level was somewhat arbitrary. It was based on two consistent profile characteristics of the 0.60 M KCI extraction; (a) a lower total yield of ribosomes from the tissue (less area under the curve) was observed, and (b) an apparent dissociation of monosomes to subunits as a result of replacement of Mg`by the monovalent ion (20,22).…”

Section: Resultsmentioning

confidence: 95%

Requirement for Extraction of Polyribosomes from Barley Tissue

Breen¹,

Whitehead²,

Kenefick³

1972

Plant Physiol.

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Section: Resultsmentioning

confidence: 95%

Requirement for Extraction of Polyribosomes from Barley Tissue

Breen¹,

Whitehead²,

Kenefick³

1972

Plant Physiol.

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“…The importance of an equilibrium has not been seriously considered heretofore and its presence would influence details of current models for the role of single ribosomes in protein synthesis (18,19 (20,21). Our results highlight the danger inherent in assigning sedimentation coefficients to ribosomal particles without taking into account possible effects of pressure on the equilibrium between ribosomes and subunits.…”

Section: Discussionmentioning

confidence: 90%

Pressure-Induced Dissociation of Sedimenting Ribosomes: Effect on Sedimentation Patterns

Infante

Baierlein

1971

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

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Anomalous sedimentation patterns arise when free ribosomes from sea urchin eggs are centrifuged at high speeds. Pressure-induced dissociation of the ribosomes during sedimentation can explain the peculiar behavior; the assumption of such dissociation also yields estimates of the equilibrium constant (as a function of KCI concentration) and the change in molecular volume (500 i 100 ml/mol) in the reaction: subunits :± ribosome. Such dissociation during centrifugation may explain many experiments in which apparent reduced sedimentation coefficients for ribosomes, and increased coefficients for the subunits, have been ascribed to conformational changes.Anomalies in the sedimentation characteristics of ribosomes and subunits under various ionic conditions have been reported in many studies. These results have been generally interpreted in terms of conformational changes in the ribosomes and ribosomal subunits (1-7). However, a recent study (8) showed that the sedimentation pattern of free ribosomes from sea urchins is strongly dependent not only on the ionic conditions but also on the gravitational field and the concentration of ribosomes. When these factors are appropriately varied, the ribosomes display an apparently reduced sedimentation velocity or dissociate into subunits of apparently increased velocities. The results were interpreted in terms of (a) the dissociation of ribosomes at a rather distinct point during ultracentrifugation, and (b) the notion that the dissociation is due to a shift in the equilibrium between subunits and ribosomes in the sucrose gradient.The cause of this dissociation is suggested by the results of studies of protein dissociation, which have shown that the high pressure experienced by particles in the analytical ultracentrifuge can induce dissociation of multimers into subunits if thejnolecular volume decreases upon dissociation (for a general treatment of this subject, see refs. 9 and 10). Some of these ideas were formulated by Josephs and Harrington (11,12) arudwere used to explain the anomalous sedimentation of myosin. In this report, we examine the effect of hydrostatic pressure on the dissociation of ribosomes during zonal centrifugation in sucrose gradients. We conclude that pressure does induce the 75S free ribosomes to dissociate into their 56S and 35S subunits, and that this behavior can explain various peculiar sedimentation patterns of both eukaryotic and prokaryotic ribosomes that had previously been ascribed to conformational changes. MATERIALS AND METHODSUnfertilized eggs of the sea urchin, Strongylocentrotus purpuratus, were used in these studies, since the bulk (>95%) of the ribosomes from this source are not complexed with mRNA and peptidyl-tRNA (8). The procedures used to obtain cell-free homogenates are described in detail elsewhere (13,8). The eggs were homogenized in TM buffer containing 0.25 M sucrose and the indicated concentrations of KCl. (TM buffer contains 5 mM MgCl2-50 mM triethanolamine, pH 7.8.) A 15,000 X g supernatant (S15) was prepared and ana...

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“…Liver ribosomes were isolated from male Sprague-Dawley rats that weighed 100-120 g (5,6) and used to prepare ribosomal subunits (5,7).…”

Section: F2p]atp and [Y-32p]gtp (4)mentioning

confidence: 99%

A Kinase That Transfers the γ-Phosphoryl Group of GTP to Proteins of Eukaryotic 40S Ribosomal Subunits

Ventimiglia

Wool

1974

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

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An enzyme in rat-liver cytosol transferred the 7y-phosphoryl of GTP to serine and threonine residues of at least four proteins (S6, S10, S14 or S15, and S17) of the small (40S) subunit of rat-liver ribosomes. A number of nonribosomal proteins in the enzyme preparation were also phosphorylated; they were preferentially and tightly bound to the large subunit. The enzyme could be distinguished from protein kinase-ATP (which also phosphorylated ribosomal proteins) by a number of criteria: (1) GTP was the phosphoryl donor; (2) the pattern of phosphorylation of ribosomal proteins by the two enzymes was different; and (3) the protein kinase that used GTP as the phosphoryl donor was not stimulated by cyclic AMP (or by cyclic GMP).Eukaryotic ribosomal proteins are phosphorylated in vivo and in vitro by protein kinases bound to the particle or free in the cytoplasm (1-3); that reaction has been shown, or assumed, to result from the transfer of phosphate from ATP. We report now on a related but novel reaction. There is an enzyme ac--tivity in rat-liver cytosol that catalyzes the transfer of the yphosphoryl of GTP to several proteins of the 40S subunit of eukaryotic ribosomes. Preparation of Ribosomal Subunits. Liver ribosomes were isolated from male Sprague-Dawley rats that weighed 100-120 g (5, 6) and used to prepare ribosomal subunits (5, 7).Preparation of Enzymes. The enzyme responsible for the transfer of the y-phosphoryl of GTP to ribosomal protein was prepared from rat-liver cytosol by hydroxylapatite chromatography, followed by filtration through Sephadex G-200, using the protocol described by Schneir and Moldave (9) for the isolation of elongation factor 1 (EF-1). We refer to the activity as "protein kinase-GTP." A rat-liver protein kinase that transfers the y-phosphoryl group of ATP to serine and theonine in ribosomal proteins was prepared as described (3, 10); the enzyme is referred to as "protein kinase-

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Dissociation and reassociation of skeletal muscle ribosomes

Cited by 156 publications

References 15 publications

Requirement for Extraction of Polyribosomes from Barley Tissue

Requirement for Extraction of Polyribosomes from Barley Tissue

Pressure-Induced Dissociation of Sedimenting Ribosomes: Effect on Sedimentation Patterns

A Kinase That Transfers the γ-Phosphoryl Group of GTP to Proteins of Eukaryotic 40S Ribosomal Subunits

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