Compartmentation of uridine 5′-triphosphate occurs during synthesis of cytoplasmic and mitochondrial ribosomal RNAs of cultured tomato cells but not during synthesis of cytoplasmic ribosomal and transfer RNAs

摘要

Compartmentation of uridine 5′-triphosphate (UTP) was studied during the nucleolar synthesis of cytoplasmic ribosomal RNA (cyt-rRNA) and the synthesis of cytoplasmic transfer RNA (cyt-tRNA) in the nuclear matrix as well as the synthesis of mitochondrial ribosomal RNA (mt-rRNA) in tomato (Lycopersicon esculentumMill. cv. Lukullus) cell-suspension culture using the approach of Wiegers et al. (Eur. J. Biochem.64, 535–540, 1976). Before measurements were made, it was ensured that: (i) there was steady-state labeling of all RNAs studied as well as UTP; (ii) there was stability of cyt-tRNA and cyt-rRNA; (iii) there was no label randomization through degradation of 3Huridine; (iv) there were significant differences in the specific radioactivity of UTP, the final immediate precursor of RNA, after supplying the cells with two different exogenous 3Huridine concentrati