MTERF4 forms a complex with NSUN4 (Camara et al. 2011, Spahr et al. 2012, Yakubovskaya et al. 2012) and recruits NSUN4 to the ribosome where NSUN4 transfers a methyl group from S-adenosylmethionine to the 5 position of cytidine-841 in 12S rRNA (Camara et al. 2011). Knockout of MTERF4 in mice is lethal and cardiomyocyte-specific knockout is accompanied by mitochondrial cardiomyopathy (Camara et al. 2011).