RNA-binding protein involved in post-transcriptional regulation. Negatively regulates expression of COX17 by binding to the 3'-UTR of COX17 mRNA. Promotes decay of COX17 mRNA by enhancing its rate of deadenylation and subsequent turnover. Predominantly binds to mRNAs encoding mitochondrial proteins and localizes them to the vicinity of mitochondria for translation. Regulates mitochondrial biogenesis, motility and morphology. Localizes to multiple discrete foci in the cytoplasm. Present with 846 molecules/cell in log phase SD medium. Belongs to the PUF3 family.