Open AccessPolypeptide chain initiation in eukaryotes: mechanism of formation of initiation complex.
Author(s) -
César Nombela,
N. A. Nombela,
S Ochoa,
B Safer,
W. French Anderson,
William C. Merrick
Publication year - 1976
Publication title -
proceedings of the national academy of sciences
Language(s) - English
Resource type - Journals
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.73.2.298
Subject(s) - puromycin , gtp' , chemistry , complex formation , ribosome , eif2 , eukaryotic translation , aminoacyl trna , protein subunit , eukaryotic small ribosomal subunit , initiation factor , biophysics , microbiology and biotechnology , biochemistry , stereochemistry , biology , translation (biology) , protein biosynthesis , rna , enzyme , messenger rna , inorganic chemistry , gene
Artemia salina ribosomal subunits and highly purified reticulocyte initiation factors (IF) are used to study the mechanism of formation of the puromycin-sensitive initiation complex Met-tRNAi-80S ribosome-AUG. A complex with equimolar amounts of 40S subunit, GTP, and Met-tRNAi is formed at low Mg2+ concentration with a requirement for IF-MP (homogeneous) but not AUG or other factors. An 80S complex is formed only upon the further addition of AUG, IF-M2A, and IF-M2B, but not of either factor alone. This complex contains no GTP or GDP. A 40S complex, which cannot be converted to an 80S one, is formed when the nonhydrolyzable analog GMPPCP is substituted for GTP. IF-M2A has no effect on the formation of this complex, but IF-M2B enhances its formation.
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