Regulation of Cerebral Metabolism of Amino Acids—iii

Zomzely, Claire; Roberts, Sidney; Rapaport, Deborah

doi:10.1111/j.1471-4159.1964.tb11454.x

Cited by 79 publications

(24 citation statements)

References 8 publications

(7 reference statements)

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“…Our results, which are in general agreement with those of Satake et al (1964), Murthy and Rappaport (1965), Suzuki et al (1964), and Zomzely et al (1964), indicate that brain ribosomal cell-free systems are similar to other mammalian systems in many respects. The ATP, GTP, potassium, magnesium, and GSH requirements are virtually identical with those of reticulocyte (Allen and Schweet, 1962) and liver (Sachs, 1957) systems.…”

Section: Discussionsupporting

confidence: 91%

In Vitro Synthesis of Brain Protein. II. Properties of the Complete System^*

Stenzel¹,

Aronson²,

Rubin³

1966

Biochemistry

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Ribosomes and microsomes prepared from rabbit brain are active in protein synthesis. The requirements for optimal incorporation are similar to those of other mammalian cell-free systems, and include adenosine 5'-triphosphate (ATP) and an ATP regenerating system, guanosine-5 '-triphosphate (GTP), pH 5 fraction, potassium, and magnesium. Amino acids are required for optimal activity in the ribosomal system. Glutamic acid alone restores 9&95% of full activity in the absence of an amino acid mixture. Ribo-T he role of proteins in the specific functions of nervous tissue is not known. Molecular theories of neuronal transmission and memory require that macromolecular substances subserve specific roles in either impulse propagation, synaptic transmission, or recognition of specific neuronal circuits (Schmitt, 1964). Cellfree systems derived from brain are of interest not only

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Section: Discussionsupporting

confidence: 91%

In Vitro Synthesis of Brain Protein. II. Properties of the Complete System^*

Stenzel¹,

Aronson²,

Rubin³

1966

Biochemistry

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“…of buffer A (0.25 M-sucrose; 0.025 M-KCl; 0004 M-MgOAc; 0.05 M-tris-HCI, pH 7.4) using 10 strokes of the pestle of a motor-driven Potter-Elvehjem homogenizer. Microsomes and pH 5 fractions were prepared by differential centrifugation and acid precipitation respectively (ZOMZELY, ROBERTS and RAPPAPORT, 1964).…”

Section: Preparation Of Microsomes and P H 5 Fractionsmentioning

confidence: 99%

POLYRIBOSOME DISAGGREGATION AND CELL‐FREE PROTEIN SYNTHESIS IN PREPARATIONS FROM CEREBRAL CORTEX OF HYPERPHENYLALANINEMIC RATS¹

Siegel¹,

Aoki

Colwell³

1971

Journal of Neurochemistry

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Abstract— Seven‐day‐old rats were injected intraperitoneally with l‐phenylalanine (1 g/kg) and the time course of brain polyribosome disaggregation and changes in brain levels of phenylalanine, tryptophan and tyrosine were determined. Disaggregation of brain polyribosomes preceded the increase in levels of phenylalanine in brain, and followed the same time course as depletion of tryptophan from brain. The effects of several metabolites of phenylalanine (which are formed in phenylketonuria) on protein synthesis in vitro was determined for brain and liver systems. None of the compounds tested was inhibitory at concentrations below 10 mM and in all cases hepatic protein synthesis was more sensitive to inhibition than was the corresponding system from brain. Ribosomal dimers, formed in brain after injection of phenylalanine, were incapable of supporting high levels of protein synthesis in vitro, a finding that suggested that the inhibition of protein synthesis in vitro in cell‐free systems of brain tissue after injection of phenylalanine into young rats was mediated by disaggregation of brain polyribosomes associated with tryptophan deficiency in brain.

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“…Preliminary incubation for 5-20 min resulted in progressive enhancement of the subsequent response to cerebral nuclear RNA. As anticipated, preliminary incubation of brain ribosomes in the presence of pH 5 fraction markedly reduced incorporation of endogenous amino acids during the subsequent incubation period (ZOMZELY et al, 1968). However, the actual decrease was variable from one experiment to another and was an important factor affecting the observed response to nuclear RNA.…”

Section: Factors Affecting the Stimulation Of Incorporation Of Amino mentioning

confidence: 51%

PROPERTIES OF RNA FRACTIONS FROM NUCLEI OF BRAIN CELLS WHICH STIMULATE INCORPORATION OF AMINO ACIDS BY BRAIN RIBOSOMES¹

Samli

Roberts

1969

Journal of Neurochemistry

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Abstract— The properties of RNA fractions from nuclei of brain cells which were capable of stimulating amino acid incorporation into proteins of an homologous ribosomal system were investigated. RNA was routinely prepared from crude nuclear preparations of rat brain by a method which involved treatment with sodium dodecyl sulphate and phenol at 65°. The capacity of this preparation to stimulate incorporation of radioactivity from a mixture of 15 l‐[14C]amino acids was greatly enhanced by preliminary incubation of the ribosomal system from brain for 5–20 min. The response was markedly dependent upon the concentrations of ribosomes and of the pH 5 fraction. The optimal level of Mg2+ for basal incorporation of amino acids into protein was 8 mm; however, incorporation in the presence of nuclear RNA was greater at higher concentrations of Mg2+. The response to nuclear RNA was also enhanced as the K+ concentration was increased from 25 to 100 mm. The stimulatory effect of nuclear RNA on incorporation of l‐[12C]eucine was either unaltered or depressed by addition of a mixture of 19 l‐[12C]amino acids each at concentrations, of 10−8, 10−2, or 10−1 mm. Under appropriate conditions of incubation, basal rates of incorporation and rates of incorporation stimulated by nuclear RNA were linear for 30 min. The response was proportional to the concentration of nuclear RNA between 34 and 136 μg. RNA prepared from ribosomes of rat brain essentially failed to stimulate incorporation of amino acids over this range of concentrations. Fractionation of nuclear RNA by centrifugation in sucrose density gradients revealed that 75 per cent of the stimulatory activity was in the fraction which sedimented below 12 S and contained about 25 per cent of the total RNA. Most of the remaining activity was in the 18 S region. Less than 5 per cent of the RNA in the lightest fraction (< 12 S) exhibited amino acid‐acceptor activity, The stimulatory action of nuclear RNA on incorporation of amino acids was readily destroyed by mild treatment with pancreatic ribonuclease, whereas amino acid‐acceptor activity was relatively resistant to this treatment. The results suggest that the brain may contain low molecular weight RNA with properties of messenger RNA.

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Regulation of Cerebral Metabolism of Amino Acids—iii

Cited by 79 publications

References 8 publications

In Vitro Synthesis of Brain Protein. II. Properties of the Complete System^*

In Vitro Synthesis of Brain Protein. II. Properties of the Complete System^*

POLYRIBOSOME DISAGGREGATION AND CELL‐FREE PROTEIN SYNTHESIS IN PREPARATIONS FROM CEREBRAL CORTEX OF HYPERPHENYLALANINEMIC RATS¹

PROPERTIES OF RNA FRACTIONS FROM NUCLEI OF BRAIN CELLS WHICH STIMULATE INCORPORATION OF AMINO ACIDS BY BRAIN RIBOSOMES¹

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Regulation of Cerebral Metabolism of Amino Acids—iii

Cited by 79 publications

References 8 publications

In Vitro Synthesis of Brain Protein. II. Properties of the Complete System*

In Vitro Synthesis of Brain Protein. II. Properties of the Complete System*

POLYRIBOSOME DISAGGREGATION AND CELL‐FREE PROTEIN SYNTHESIS IN PREPARATIONS FROM CEREBRAL CORTEX OF HYPERPHENYLALANINEMIC RATS1

PROPERTIES OF RNA FRACTIONS FROM NUCLEI OF BRAIN CELLS WHICH STIMULATE INCORPORATION OF AMINO ACIDS BY BRAIN RIBOSOMES1

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In Vitro Synthesis of Brain Protein. II. Properties of the Complete System^*

In Vitro Synthesis of Brain Protein. II. Properties of the Complete System^*

POLYRIBOSOME DISAGGREGATION AND CELL‐FREE PROTEIN SYNTHESIS IN PREPARATIONS FROM CEREBRAL CORTEX OF HYPERPHENYLALANINEMIC RATS¹

PROPERTIES OF RNA FRACTIONS FROM NUCLEI OF BRAIN CELLS WHICH STIMULATE INCORPORATION OF AMINO ACIDS BY BRAIN RIBOSOMES¹