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Initiation of protein biosynthesis in eukaryotes
Author(s) -
Merrick William C.
Publication year - 2003
Publication title -
biochemistry and molecular biology education
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.34
H-Index - 39
eISSN - 1539-3429
pISSN - 1470-8175
DOI - 10.1002/bmb.2003.494031060274
Subject(s) - eif2 , eukaryotic initiation factor , translation (biology) , transfer rna , initiation factor , biology , eukaryotic translation , protein biosynthesis , messenger rna , protein subunit , translational regulation , microbiology and biotechnology , gtp' , biochemistry , rna , gene , enzyme
Initiation of protein synthesis in eukaryotes is important both mechanically, because it selects the translation reading frame, and biologically, because it is the primary site for regulation of translation. For approximately 95–98% of the cellular mRNAs, formation of an initiation complex follows a rather specific pathway that is broken down into seven discrete steps. Although almost 35 peptides in 12–14 translation initiation factors participate in this process, three appear to have dominant roles: eukaryotic initiation factor (eIF)3, in building a pool of 40S subunits; eIF2, in binding the initiator tRNA (tRNA i ) to the 40S subunit; and eIF4F in activating the mRNA and binding it to the 40S subunit. This process requires both ATP and GTP. The resulting 80S initiation complex contains both the tRNA i and the mRNA, with the anticodon of the tRNA i correctly base paired with the initiating AUG code word. Regulation of translation focuses mostly on controlling the activity of either eIF2 or eIF4F and this regulation has different consequences. Reduction in eIF2 activity influences all mRNA approximately the same, whereas reduction in eIF4F activity drives competition between mRNAs.