As a component of the mitochondrial large ribosomal subunit, it plays a role in mitochondrial translation (PubMed:23603806). Associates with mitochondrial RNA polymerase to activate transcription. Component of the mitochondrial large ribosomal subunit (mt-LSU) (PubMed:8626705). Mature mammalian 55S mitochondrial ribosomes consist of a small (28S) and a large (39S) subunit. The 28S small subunit contains a 12S ribosomal RNA (12S mt-rRNA) and 30 different proteins. The 39S large subunit contains a 16S rRNA (16S mt-rRNA), a copy of mitochondrial valine transfer RNA (mt-tRNA(Val)), which plays an integral structural role, and 52 different proteins (Probable). bL12m interacts with NOA1 (PubMed:19103604). The disease may be caused by variants affecting the gene represented in this entry. Belongs to the bacterial ribosomal protein bL12 family.