Age-dependent changes in the specificity of tRNA methyltransferases in the cerebellum of the icteric and nonicteric Gunn rat |
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| Authors: | Jacques Dainat F de Balbian Verster R Zand O Z Sellinger |
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| Institution: | (1) Laboratory of Neurochemistry, Mental Health Research Institute, University of Michigan, 48109 Ann Arbor, Michigan;(2) Division of Biophysics, Institute of Science and Technology, University of Michigan, 48109 Ann Arbor, Michigan;(3) Department of Biological Chemistry, University of Michigan, 48109 Ann Arbor, Michigan;(4) Present address: Laboratoire de Neuroendocrinologie, Université des Sciences et Techniques du Languedoc, Montpellier, Cedex, 34, France |
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| Abstract: | The activity of tRNA methyltransferases present in the cerebellum of 6- and 21-day-old nonicteric and icteric Gunn rats was compared using purifiedE. coli tRNAs as substrates. At 6 days the tRNA methyltransferases of the icteric animals were significantly more effective in methylating tRNAGlu
2 and tRNAPhe than were those of their nonicteric counterparts. This relationship reversed itself at 21 days. The action of the tRNA methyltransferases from the 6-day-old icteric animals led to higher proportions of 1-methyladenine in tRNAGlu
2 and tRNAPhe than were obtained using the corresponding enzymes of the nonicteric animals. The proportion ofN
2-methylguanine was also higher, yet only in tRNAfMet and not in tRNAPhe. The study reveals much more extensive fluctuations in the activity and in the substrate recognition specificity among the cerebellar tRNA methyltransferases of the icteric than among those of the nonicteric controls during the crucial 6–21 day period of cerebellar development. |
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