The Binding of Met-tRNAf to Isolated 40-S Ribosomal Subunits and the Formation of Met-tRNAf . 80-S-Ribosome Initiation Complexes
نویسندگان
چکیده
منابع مشابه
Binding of Met-tRNAf to native 40 S ribosomal subunits in Ehrlich ascites tumor cells.
Two forms of native 40 S ribosomal subunits, distinguishable by their buoyant densities, are recovered from Ehrlich ascites cells. In this communication, we describe experiments designed to test whether Met-tRNAf is associated with either form. Our results indicate that (a) in the cell, Met-tRNAf is bound to the native 40 S subunit, and in particular, to the subunit of density 1.40 g x cm-3; (b...
متن کاملPreparation and characterization of eukaryotic initiation factor EIF-3. Formation of binary (EIF-3-Met-tRNAf) and ternary (EIF-3-Met-tRNAf-GTP) complexes.
The 133,000 X g supernatant fraction prepared from ascites cells in 20 mM KCl (low CKl supernatant) contained the initiation factors EIF-1 and EIF-2 (and the elongation factore EF-1 and EF-2) but lacked EIF-3; thus, low KCl supernatant could be used to assay for EIF-3. EIF-3 was prepared from a crude initiation factor perparation (a 250 mM KCl extract of ascites cell ribosomes precipitated with...
متن کاملCharacterization of GTP-dependent Met-tRNAf binding protein.
Purified GTP-dependent Met-tRNAf binding protein (EIF2) prepared from the 0.5 M KCl eluate of reticulocyte polyribosomes was successfully resolved into its three-component subunits by isoelectric focusing in the presence of urea. The 37,000-dalton subunit focused at a pH of 5.8 and was resolved into two spots; the 48,000-dalton subunit focused at a pH of 6.6 and was resolved into three spots; a...
متن کاملStudies on the mechanism of action of a eukaryotic codon-dependent factor specific for initiator Met-tRNAf and ribosomal 40 S subunits.
A putative eukaryotic initiation factor purified from rat liver cytosol promotes the ApUpGp- and Mg2+-dependent, GTP-independent binding of initiator Met-tRNAf to ribosomal 40 S subunits. The isotopically-labeled factor binds specifically to 40 S subunits to form a binary complex which can then bind Met-tRNAf in the presence of ApUpGp. When 60 S subunits are added, an 80 S complex is formed whi...
متن کاملBinding of MET-TRNAf and GTP to homogeneous initiation factor MP.
Homogeneous initiation factor MP forms a stable complex with Met-tRNAf which binds to nitrocellulose filters in the absence of ribosomal subunits. Complex formation is rapid at 0 degrees and the rate of reaction is stimulated 20-fold by GTP when freshly prepared initiation factor MP is used. Under optimal assay conditions, a 1:1:1 stoichiometry for initiation factor MP, GTP, and Met-tRNAf is in...
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ژورنال
عنوان ژورنال: European Journal of Biochemistry
سال: 1976
ISSN: 0014-2956,1432-1033
DOI: 10.1111/j.1432-1033.1976.tb10154.x