Component of the mitochondrial ribosome (mitoribosome), a dedicated translation machinery responsible for the synthesis of mitochondrial genome-encoded proteins, including at least some of the essential transmembrane subunits of the mitochondrial respiratory chain. The mitoribosomes are attached to the mitochondrial inner membrane and translation products are cotranslationally integrated into the membrane (PubMed:14566057, PubMed:25609543, PubMed:28154081). mS47 has enzymatic activity in vitro, and is able to catalyze the specific hydrolysis of 3-hydroxyisobutyryl-CoA (HIBYL-CoA). However, because the turnover rate of mS47/EHD3 is only a fraction of that of the homologous mammalian enzyme, the physiological function of this activity remains unclear (PubMed:12697341). Has an indirect role in endocytic membrane trafficking (PubMed:11378903). 3-hydroxy-2-methylpropanoyl-CoA + H2O = 3-hydroxy-2-methylpropanoate + CoA + H(+) Component of the mitochondrial small ribosomal subunit (mt-SSU). Mature yeast 74S mitochondrial ribosomes consist of a small (37S) and a large (54S) subunit. The 37S small subunit contains a 15S ribosomal RNA (15S mt-rRNA) and 34 different proteins. The 54S large subunit contains a 21S rRNA (21S mt-rRNA) and 46 different proteins. mS47 forms a protuberance of the yeast mitoribosome and retains a solvent-exposed cavity liekly capable of accommodating a substrate, in accordance with it being an active enzyme as well as an integral constituent of the mitoribosome. Mitoribosomes are tethered to the mitochondrial inner membrane and spatially aligned with the membrane insertion machinery through two distinct membrane contact sites, formed by the 21S rRNA expansion segment 96-ES1 and the inner membrane protein MBA1. Present with 3950 molecules/cell in log phase SD medium. Belongs to the enoyl-CoA hydratase/isomerase family. Mitochondrion-specific ribosomal protein mS47 subfamily.