We have characterized a new delayed-early response mRNA encoding a 21-kDa product (MRPL12) that accumulates during the G1 phase of growth-stimulated cells. MRPL12 is the mammalian homologue to chloroplastic and bacterial L12 ribosomal proteins. Immunofluorescence microscopy and cell fractionation indicate a predominant mitochondrial localization in various mammalian cell lines. The NH2-terminal 49 amino acids are necessary and sufficient to target the protein within the mitochondria and are probably cleaved off during import. MRPL12 proteins associated in vitro and cofractionate with ribosomal structures, as is the case for prokaryotic L12 proteins. Expression of a dominant inhibitory truncated protein leads to a severe reduction in cell growth by inhibiting mitochondrial ATP production. MRPL12 is the first mammalian mitochondrial ribosomal protein to be characterized.
A delayed-early response nuclear gene encoding MRPL12, the mitochondrial homologue to the bacterial translational regulator L7/L12 protein
Marty, L.; Fort, P.
J Biol Chem
1996-05-10 / vol 271 / pages 11468-76
Humans; Animals; Mice; Amino Acid Sequence; Molecular Sequence Data; Base Sequence; Cell Line; Gene Expression; Oligodeoxyribonucleotides; Escherichia coli/metabolism; Mitochondria/*metabolism; Sequence Homology, Amino Acid; Cricetinae; Phylogeny; Hela Cells; Cercopithecus aethiops; Cell Division; Protein Biosynthesis; *Cell Cycle Proteins; Cloning, Molecular; DNA, Complementary; 3T3 Cells; Bacillus stearothermophilus/metabolism; Bacterial Proteins/metabolism; Cell Nucleus; Chloroplasts/metabolism; Glutathione Transferase/biosynthesis; Nuclear Proteins/*biosynthesis/*genetics/metabolism; Recombinant Fusion Proteins/biosynthesis/metabolism; Ribosomal Proteins/*biosynthesis/*genetics/*metabolism; Ribosomes; Spinacia oleracea