Effects of cycloleucine on mitochondrial RNA
Mitochondria contain their own genetic system, which specifies not only the mRNA’s for a particular set of proteins but also the ribosomal and transfer RNA’s required for translating these mRNA’s. In mammalian mitochondria the ribosomal and most transfer RNA’s are methylated, as would be expected for rRNA and tRNA, but in distinctive fashion. The rRNA’s have very few methylated residues, 5 per molecule for the small subunit (“13S”) RNA and 3 per molecule for the large subunit (“17S”) RNA, or about 20 to 50% as many as the homologous E. coli prototypes (Dubin & Taylor, 1978; Dubin et al, 1978). The tRNA contains about 2 methylated residues on the average per molecule, a figure which resembles that for E. coli and is 1/3 that for cytoplasmic tRNA; its methylated nucleoside composition constitutes a subset of that of cytoplasmic (cyt) tRNA, only m3C, m5C, m1A, m1G, m2G, and m22G being present in significant amounts (Dubin & Friend, 1974; Davenport et al, 1976).
KeywordsMethionine Metabolism Mammalian Mitochondrion Standard Salt Apparent Degree Density Gradient Sedimentation
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