Translation elongation proceeds by cycles of aminoacyl-tRNAs binding, peptide bond formation, and displacement of deacylated tRNAs (reviewed in Christian and Spremulli 2012). In each cycle an aminoacyl-tRNA in a complex with TUFM:GTP (EF-Tu:GTP) binds a cognate codon at the A-site of the ribosome, GTP is hydrolyzed, and TUFM:GDP dissociates. The elongating polypeptide bonded to the tRNA at the P-site is transferred to the aminoacyl group at the A-site by peptide bond formation, leaving a deacylated tRNA at the P-site and the elongating polypeptide attached to the tRNA at the A-site. GFM1:GTP (EF-Gmt:GTP) binds, GTP is hydrolyzed, GFM1:GDP dissociates, and the ribosome translocates 3 nucleotides in the 3' direction, relocating the peptidyl-tRNA to the P-site and allowing another cycle to begin. Mitochondrial ribosomes associate with the inner membrane and polypeptides are co-translationally inserted into the membrane (reviewed in Ott and Herrmann 2010, Agrawal and Sharma 2012). TUFM:GDP is regenerated to TUFM:GTP by the guanine nucleotide exchange factor TSFM (EF-Ts, EF-TsMt).