Elongation factor G,Mouse,itochondrial (GFM1) is a mitochondrial GTPase that plays a central role in protein elongation by promoting the GTP-dependent translocation of the nascent protein chain from the A-site to the P-site of the ribosome. GFM1 does not mediate the disassembly of ribosomes from messenger RNA at the termination of mitochondrial protein biosynthesis. Defects in GFM1 are the cause of combined o, Xenopus/Amphibian,idative phosphorylation deficiency type 1 (CO, Xenopus/Amphibian,PD1), a condition that leads to early fatal progressive hepatoencephalopathy.