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Publication Abstract from PubMed

The human mitochondrial translational initiation factor 3 (IF3mt) carries mitochondrial-specific amino acid extensions at both its N and C termini (N- and C-terminal extensions [NTE and CTE, respectively]), when compared with its eubacterial counterpart. Here we present 3.3- to 3.5-A-resolution cryoelectron microscopic structures of the mammalian 28S mitoribosomal subunit in complex with human IF3mt. Unique contacts observed between the 28S subunit and N-terminal domain of IF3mt explain its unusually high affinity for the 28S subunit, whereas the position of the mito-specific NTE suggests NTE's role in binding of initiator tRNA to the 28S subunit. The location of the C-terminal domain (CTD) clarifies its anti-association activity, whereas the orientation of the mito-specific CTE provides a mechanistic explanation for its role in destabilizing initiator tRNA in the absence of mRNA. Furthermore, our structure hints at a possible role of the CTD in recruiting leaderless mRNAs for translation initiation. Our findings highlight unique features of IF3mt in mitochondrial translation initiation.

Structure of Human Mitochondrial Translation Initiation Factor 3 Bound to the Small Ribosomal Subunit.,Koripella RK, Sharma MR, Haque ME, Risteff P, Spremulli LL, Agrawal RK iScience. 2019 Feb 22;12:76-86. doi: 10.1016/j.isci.2018.12.030. Epub 2019 Jan 3. PMID:30677741^[2]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.