Evolution of proteins in mammalian cytoplasmic and mitochondrial ribosomes

The proteins of cytoplasmic and mitochondrial ribosomes from the cow and the rat were analyzed by co-electrophoresis in two dimensional polyacrylamide gels to determine their relative evolutionary rates. In a pairwise comparison of individual ribosomal proteins (r-proteins) from the cow and the rat,...

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Bibliographic Details
Published in:Journal of molecular evolution 1986-01, Vol.24 (1-2), p.110-117
Main Authors: PIETROMONACO, S. F, HESSLER, R. A, O'BRIEN, T. W
Format: Article
Language:English
Subjects:
Animals
Biological and medical sciences
Biological Evolution
Cattle
Chickens
cytoplasm
Cytoplasm - metabolism
evolution
Fundamental and applied biological sciences. Psychology
gel electrophoresis
Genetics of eukaryotes. Biological and molecular evolution
Humans
mitochondria
Mitochondria - metabolism
Rabbits
Rats
ribosomal proteins
Ribosomal Proteins - genetics
Ribosomal Proteins - isolation & purification
Ribosomes - metabolism
Species Specificity
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Summary:The proteins of cytoplasmic and mitochondrial ribosomes from the cow and the rat were analyzed by co-electrophoresis in two dimensional polyacrylamide gels to determine their relative evolutionary rates. In a pairwise comparison of individual ribosomal proteins (r-proteins) from the cow and the rat, over 85% of the cytoplasmic r-proteins have conserved electrophoretic properties in this system, while only 15% of the proteins of mitochondrial ribosomes from these animals fell into this category. These values predict that mammalian mitochondrial r-proteins are evolving about 13 times more rapidly than cytoplasmic r-proteins. Based on actual evolutionary rates for representative cytoplasmic r-proteins, this mitochondrial r-protein evolutionary rate corresponds to an amino acid substitution rate of 40 X 10(-10) per site per year, placing mitochondrial r-proteins in the category of rapidly evolving proteins. The mitochondrial r-proteins are apparently evolving at a rate comparable to that of the mitochondrial rRNA, suggesting that functional constraints act more or less equally on both kinds of molecules in the ribosome. It is significant that mammalian mitochondrial r-proteins are evolving more rapidly than cytoplasmic r-proteins in the same cell, since both sets of r-proteins are encoded by nuclear genes. Such a difference in evolutionary rates implies that the functional constraints operating on ribosomes are somewhat relaxed for mitochondrial ribosomes.
ISSN:0022-2844
1432-1432
DOI:10.1007/BF02099958