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PROTEIN SYNTHESIS IN FRACTIONS FROM ISOLATED BRAIN CELL NUCLEI |
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| Authors: | J. A. Burdman K. Haglid A. R. Dravid |
| Affiliation: | Laboratory of Neurobiology, National Institute of Mental Health, Bethesda, Maryland and Institute of Neurobiology, Faculty of Medicine, University of Gothenburg, Gothenburg, Sweden |
| Abstract: | Abstract— 1. The incorporation in vivo and in vitro of isotopically labelled leucine into fractions of nuclear proteins from young and adult rat brain was investigated. 2. During post-natal cerebral maturation, the ability of nuclei from brain cells to synthesize proteins decreased. The specific activities of all the fractions of nuclear protein were highest in 3-day-old rats and declined thereafter. Nuclei from adult brain cells exhibited only 10 per cent of the activity found in nuclei from brain cells of 3-day-old rats. 3. The 'residual protein' fraction was most rapidly labelled, peak activity being reached within 30 min after injection. In vitro , the 'residual protein' fraction attained maximum activity within 40 min. 4. The specific activity of the chromatin acidic proteins (HCl-insoluble) was considerably higher than that of the histones both in vivo and in vitro. Histones were the most inert of all the nuclear protein fractions studied. The possible functional significance of the various protein fractions during the process of cerebral maturation and in the adult brain is discussed. |
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