Mitochondrion genome

Thyroid hormone mechanisms of action can be classified into two types (1) genomic or nuclear and (2) nongenomic, including effects at the plasma membrane and mitochondria. Genomic effects involve modification of gene transcription, are mediated only by Tj, and require at least several hours to detect. Nongenomic actions are generally rapid in onset and occur in response to T4 and some T4 metabolites (e.g., rT3,T3, and Tj). 

Goyeneche AA, Harmon JM, Telleria CM (2006) Cell death induced by serum deprivation in luteal cells involves the intrinsic pathway of apoptosis. Reproduction 131 103-111 Gray MW, Burger G, Lang BF (2001) The origin and early evolution of mitochondria. Genome Biol 2 1018.1-1081.5... 

There seems to be no explicit proposal for the most widely held hypothesis for the persistence of mitochondria genomes, but the hypothesis is implicit in many discussions of mitochondrial structure and function. For example, and in contrast to the open question posed by Alberts et al., Cell and Molecular Biology Concepts and Experiments (Karp 2002) provides what is probably still the current consensus view. 

Sylvestre J, Vialette S, Corral Debrinski M, Jacq C (2003) Long mRNAs coding for yeast mitochondrial proteins of prokaryotic origin preferentially localize to the vicinity of mitochondria. Genome Biol 4 R44... 

Type of expression vector Destination of expressed protein Regulation of protein biosynthesis Piasmids, mitochondria, genome Intraceiluiar, perisplasm, exracellular Constitutive expression, induction... 

Mitochondria are unique organelles in man and higher animals in that they contain their own genome. Mitochondrial DNA (mtDNA) in humans is a small (16.5 kb), circular genome that encodes only 13 proteins, 22 transfer RNA (tRNA), and 2 ribosomal RNA (rRNA) molecules. mtDNA is inherited only from the mother and is present in multiple copies within one mitochondrion. 

Ered Sanger, a double Nobel Prize winner, sequenced the human mitochondrial genome back in 1981. This genome codes for 13 proteins and the mitochondrion possesses the genetic machinery needed to synthesize them. Thus, the mitochondria are a secondary site for protein synthesis in eukaryotic cells. It turns out that the 13 proteins coded for by the mitochondrial genome and synthesized in the mitochondria are critically important parts of the complexes of the electron transport chain, the site of ATP synthesis. The nuclear DNA codes for the remainder of the mitochondrial proteins and these are synthesized on ribosomes, and subsequently transported to the mitochondria. 

Leon-Avila G, Tovar J (2004) Mitosomes of Entamoeba histolytica are abundant mitochondrion-related remnant organelles that lack a detectable organellar genome. Microbiol-SGM 150 1245-1250... 

In addition, both ATM1 and Ervl, which are required for the maturation of extra-mitochondrial (cytosolic) proteins and that are part of the mt export machinery, have been identified in the C. parvum genome (reviewed in Barbera et al. 2006). The former is an IM protein of the ABC transporter family that faces the mt matrix (Decottignies and Goffeau 1997), and the second is an intermembrane sulhydryl oxidase whose function in cytosolic FeS protein biosynthesis is still unknown (reviewed in Barbera et al. 2006). When combined with glutathione, which may help stabilize proteins being exported from the mitochondrion into the cytosol (reviewed in Tachezy and Dolezal... 

Each mitochondrion contains several molecules of DNA (mtDNA), usually in a closed, circular form, as well as the ribosomes, tRNA molecules, and enzymes needed for protein synthesis.1 23 26 With rare exceptions almost all of the mitochondrial DNA in a human cell is inherited from the mother.6 263 The size of the DNA circles varies from 16-19 kb in animals27 to over 200 kb in many higher plants. Complete sequences of many mitochondrial DNAs are known.28 283 Among these are the 16,569 bp human mtDNA,29 the 16,338 bp bovine mtDNA, the 16,896 bp mtDNA of the wallaroo Macropus robustus,30 and the 17,533 bp mtDNA of the amphibian Xenopus laevis.31 32 The sea urchin Paracentotus lividus has a smaller 15,697 bp genome. However, the order of the genes in this and other invertebrate mtDNA is different from that in mammalian mitochondria.33 Protozoal mtDNAs vary in size from 5900 bp for the... 

Mitochondrion. An organelle, found in eukaryotic cells, in which oxidative phosphorylation takes place. It contains its own genome and unique ribosomes to carry out protein synthesis of only a fraction of the proteins located in this organelle. 

Allen s theory of redox poise, and the evidence supporting it, are discussed in Chap. 3 of this volume. Here, I want to make a few general observations on necessity and workability. Each mitochondrion needs a genome because the speed of electron flow down the respiratory chains depends not just on supply and demand (concentration of NADH, 02, ADP and inorganic phosphate) but also on the number and redox state of respiratory complexes (Allen 1993,... 

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