期刊
BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS
卷 1750, 期 1, 页码 69-81出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.bbapap.2005.03.009
关键词
bovine; mitochondria; protein synthesis; tRNA; initiation; initiation factor 2; small ribosomal subunit
资金
- NIGMS NIH HHS [GM32734] Funding Source: Medline
Bovine mitochondrial translational initiation factor 2 (IF-2) is organized into four domains, an N-terminal domain, a central G-domain and two C-terminal domains. These domains correspond to domains III-VI in the six-domain model of Escherichia coli IF-2. Variants in IF-2(mt) were prepared and tested for their abilities to bind the small (28S) subunit of the mitochondrial ribosome. The binding of wild-type IF-2(mt) was strong (K-d similar to 10-20 nM) and was not affected by fMet-tRNA. Deletion of the N-tenninal domain substantially reduced the binding of IF2(mt) to 28S subunits. However, the addition of tMet-tRNA stimulated the binding of this variant at least 2-fold demonstrating that contacts between fMet-tRNA and IF-2(mt) can stabilize the binding of this factor to 28S subunits. No binding was observed for TF-2(mt) variants lacking the G-domain which probably plays a critical role in organizing the structure of IF-2(mt). TF-2(mt) contains a 37-amino acid insertion region between domains V and VI that is not found in the prokaryotic factors. Mutations in this region caused a significant reduction in the ability of the factor to promote initiation complex formation and to bind 28S subunits. (c) 2005 Elsevier B.V. All rights reserved.
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