Journal:Acta Cryst D:S2059798319002304
From Proteopedia
(Difference between revisions)
| Line 5: | Line 5: | ||
<hr/> | <hr/> | ||
<b>Molecular Tour</b><br> | <b>Molecular Tour</b><br> | ||
| + | Translation initiation factor 2 (e/aIF2) is essential and highly conserved in Eukarya and Archaea. In complex with GTP it is responsible for the positioning of methionylated initiator tRNA (Met-tRNAi) in the initiation complex (IC) of the ribosome. After start codon recognition the factor turns into GDP-bound form, loses affinity for Met-tRNAi and dissociates from IC. Met-tRNAi remains in the P site of the small ribosomal subunit and allows the subsequent steps of initiation process to occur. The factor consists of three subunits: alpha, beta and gamma. The largest gamma subunit (e/aIF2gamma) forms the core of the heterotrimer. It binds the alpha and beta subunits and plays the crucial role in the functioning of the protein. The gamma subunit is a G-protein and consists of three domains. Domain I (G domain) is catalytic and contains a nucleotide binding pocket and two switch regions involved in the GTP hydrolysis and the exchange of GDP to GTP. | ||
| + | In this work, the structure of aIF2gamma from Sulfolobus solfataricus obtained in the absence of magnesium ions clarified two important problems of translation initiation: | ||
| + | - magnesium ion is necessary for the formation of the active GTP-bound form of the gamma subunit. In its absence, switch 1 cannot take the form of an alpha helix and shield the phosphate moiety of GTP from the solvent. | ||
| + | - a structural motif capable of accepting two different conformations and containing strongly conserved amino acid residues was found in the domain II of the aIF2gamma and called switch 3. This switch possibly allows the codon-anticodon recognition signal to be transmitted to switch 1, causing the necessary rearrangement of this switch, which leads to the start of GTP hydrolysis and dissociation aIF2 from IC. | ||
<b>References</b><br> | <b>References</b><br> | ||
Revision as of 08:26, 14 April 2019
| |||||||||||
This page complements a publication in scientific journals and is one of the Proteopedia's Interactive 3D Complement pages. For aditional details please see I3DC.
