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Byline: S. E. Dmitriev (1), I. M. Terenin (1), M. P. Rubtsova (1), I. N. Shatsky (1) Keywords: translation initiation; [beta]-globin mRNA; mRNA secondary structure; 5'-untranslated region; initiation factor eIF2; reconstruction of the 48S initiation complex; mammals Abstract: Nucleotide sequence changes increasing the number of paired bases without producing stable secondary structure in the 5'-untranslated region (5'-UTR) of the [beta]-globin mRNA had a slight effect on its translation in rabbit reticulocyte lysate at low mRNA concentration and dramatically decreased translation efficiency at a high concentration. The removal of paired regions restored translation. Addition of purified eIF2 to the lysate resulted in equal translation efficiencies of templates differing in structure of 5'-UTR. A similar effect was observed for p50, a major mRNP protein. Other mRNA-binding initiation factors, eIF4F and eIF4B, had no effect on the dependence of translation efficiency on mRNA concentration. Analysis of the assembly of the 48S initiation complex from its purified components showed that less eIF2 is required for translation initiation on the [beta]-globin mRNA than on its derivative containing minor secondary structure elements in 5'-UTR. According to a model proposed, eIF2 not only delivers Met-tRNA, but it also stabilizes the interaction of the 40S ribosome subunit with 5'-UTR, which is of particular importance for translation initiation on templates with structured 5'-UTR. Author Affiliation: (1) Belozerskii Institute of Physico-Chemical Biology, Moscow State University, Moscow, 119899, Russia Article History: Registration Date: 12/10/2004

Byline: I. B. Khvorostov (1), M. K. Ivanov (1), G. M. Dymshits (1) Keywords: mitochondrial genome; recombination; transcription; expression regulation Abstract: The multistep regulation of mitochondrial gene expression in higher plants is considered. Data are summarized that concern the structure and function of the transcription system, posttranscriptional changes in the mRNA structure, and other levels of expression regulation. Author Affiliation: (1) Institute of Cytology and Genetics, Siberian Division, Russian Academy of Sciences, Novosibirsk, 630090, Russia Article History: Registration Date: 09/10/2004

Byline: L. P. Ovchinnikov (1), M. A. Skabkin (1), P. V. Ruzanov (1), V. M. Evdokimova (1) Keywords: mRNA; mRNP; p50; PABP; structural organization; translation; regulation; life time; actin; localization Abstract: The properties of two universal major proteins of cytoplasmic mRNP, p50 and the poly(A)-binding protein (PABP), are summarized. Their roles in formation of polyribosomal and free inactive mRNP are considered, with the focus on the authors' studies of p50. The parts these mRNP proteins play in translation regulation, stability, and localization of mRNA are described, and the possible mechanisms of their function are discussed. Author Affiliation: (1) Institute of Protein Research, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia Article History: Registration Date: 08/10/2004