Identification of mammalian mitochondrial ribosomal proteins (MRPs) by N-terminal sequencing of purified bovine MRPs and comparison to data bank sequences: the large subribosomal particle.
Bovine mitochondrial ribosomes are presented as a model system for mammalian mitochondrial ribosomes. An alternative system for identifying individual bovine mitochondrial ribosomal proteins (MRPs) by RP-HPLC is described. To identify and to characterize individual MRPs proteins were purified from bovine liver, separated by RP-HPLC, and identified by 2D PAGE techniques and immunoblotting. Molecular masses of individual MRPs were determined. Selected proteins were subjected to N-terminal amino acid sequencing. The peptide sequences obtained were used to screen different databases to identify several corresponding MRP sequences from human, mouse, rat, and yeast. Signal sequences for mitochondrial import were postulated by comparison of the bovine mature N-termini determined by amino acid sequencing with the deduced mammalian MRP sequences. Significant sequence similarities of these new MRPs to known r-proteins from other sources, e.g., E. coli, were detected only for two of the four MRP families presented. This finding suggests that mammalian mitochondrial ribosomes contain several novel proteins. Amino acid sequence information for all of the bovine MRPs will prove invaluable for assigning functions to their genes, which would otherwise remain unknown.
Graack
H R
HR
Department of Biochemistry and Molecular Biology, College of Medicine, University of Florida, Gainesville 32610-0245, USA.
Bryant
M L
ML
O'Brien
T W
TW
D000595:Amino Acid Sequence; D000818:Animals; D002417:Cattle; D006801:Humans; D051379:Mice; D008928:Mitochondria / Q000737:chemistry*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification; D051381:Rats; D000090822:Ribosomal Protein L3; D012269:Ribosomal Proteins / Q000737:chemistry / Q000302:isolation & purification*; D016415:Sequence Alignment; D020539:Sequence Analysis, Protein; D017386:Sequence Homology, Amino Acid; D013367:Submitochondrial Particles / Q000737:chemistry
D010446:Peptide Fragments; D000090822:Ribosomal Protein L3; D012269:Ribosomal Proteins; C043649:ribosomal protein L15; C029466:ribosomal protein L2; C050985:ribosomal protein L31; C041672:ribosomal protein L34