Eukaryotic initiation factor 3 does not prevent association through physical blockage of the ribosomal subunit-subunit interface.
The "native" 40 S ribosomal subunit, in which the protein eukaryotic initiation factor 3 is bound to the 40 S small ribosomal subunit, has been reconstructed to 48 A resolution. Comparison with a previous three-dimensional reconstruction of the "derived" 40 S subunit lacking any non-ribosomal components reveals the attachment site and morphology of the factor. It is a large (approximately 165 to 170 A long), bilobed, elongate structure, attached to the back lobes of the 40 S subunit by two strand-like features. Significantly, the factor is oriented away from the 60 S-subunit-40 S-subunit interface surface of the 40 S particle, suggesting that its anti-association activity is not accomplished via simple physical blockage of that surface.
Srivastava
S
S
Wadsworth Center for Laboratories and Research, N.Y.S. Dept. of Health, Albany 12201-0509.
Verschoor
A
A
Frank
J
J
D000818:Animals; D039621:Eukaryotic Initiation Factor-3; D066298:In Vitro Techniques; D046911:Macromolecular Substances; D008854:Microscopy, Electron; D010442:Peptide Chain Initiation, Translational; D010448:Peptide Initiation Factors / Q000378:metabolism*; D011817:Rabbits; D012270:Ribosomes / Q000378:metabolism* / Q000648:ultrastructure
D039621:Eukaryotic Initiation Factor-3; D046911:Macromolecular Substances; D010448:Peptide Initiation Factors