GUF1 is a 669 amino acid protein belonging to the GTP-binding elongation factor family and the LepA subfamily. Localizing to the mitochondrion inner membrane, GUF1 is thought to promote mitochondrial protein synthesis and binds to mitochondrial ribosomes in a GTP-dependent manner. GUF1 is suggested to catalyze a one-codon backward translocation of tRNAs on improperly translocated ribosomes, thereby acting as a fidelity factor of the translation reaction. GUF1 is encoded by a gene located on human chromosome 4, which encodes nearly 6% of the human genome and has the largest gene desert (regions of the genome with no protein encoding genes) of all of the human chromosomes. Defects in some of the genes located on chromosome 4 are associated with Huntington's disease, Ellis-van Creveld syndrome, methylmalonic acidemia and polycystic kidney disease.