Mitochondria structure and functions

One of the main questions is whether this sudden collapse is closely associated with the loss of mitochondria structure and function, loss of energy production, protein synthesis, and the status of cytoplasmic and/or mitochondrial GSH. 

Sbis. Ernster, L., Mitochondria. Structure and Function. Academic Press, New York, 1969. 

The CNS is not the only vulnerable tissue as red cells also rely upon a constant supply of glucose to maintain structure and function. Because they lack mitochondria, and therefore the mechanism to produce ATP via oxidative phosphorylation, RBCs are entirely dependent upon anaerobic glucose metabolism to synthesize ATP through substrate level phosphorylation. 

If we focus on the mammalian cell, we have the plasma membrane, which encompasses the cell and separates what is inside from what is outside. We also find the membranes that isolate the nucleus, the mitochondria, the lysosomes, and other intracellular organelles from the cytoplasm. AU of these membranes have their own peculiarities and distinctions. However, it is not my purpose to make a catalog of known membrane types but to provide insights into the structural and functional features that are common to many membrane types. Since we need something specific to talk about, let s focus on the plasma membrane of mammalian cells. A schematic view of such a membrane is provided in figure 19.1. 

Lesniak J, Barton WA, Nikolov DB (2002) Structural and functional characterization of the Pseudomonas hydroperoxide resistance protein Ohr. EMBO J 21 6649-6659 Lesniak J, Barton WA, Nikolov DB (2003) Structural and functional features of the Escherichia coli hydroperoxide resistance protein OsmC. Protein Sci 12 2838-2843 Lill R, Kispal G (2000) Maturation of cellular Fe-S proteins an essential function of mitochondria. Trends Biochem Sci 25 352-356 Lill R, Miihlenhoff U (2005) Iron-sulfur protein biogenesis in eukaryotes. Trends Biochem Sci 30 133-141... 

Csordas G, Renken C, Varnai P, Walter L, Weaver D, Buttle KF, BAlla T, Mannella CA, Ha-jnoczky G (2006) Structural and functional features and significance of the physical linkage between ER and mitochondria. J Cell Biol 174 915-921 Ctrnacta V, Ault JG, Stejskal F, Keithly JS (2006) Localization of pyruvate NADP+ oxi-doreductase in sporozoites of Cryptosporidium parvum. J Eukaryot Microbiol 53 225-231... 

Crofts, A.R. Berry, E.A. (1998) Structure and function of the cytochrome bci complex of mitochondria and photosynthetic bacteria. Curr. Opin. Struct. Biol. 8, 501-509. 

Tire most studied of all copper-containing oxidases is cytochrome c oxidase of mitochondria. This multisubunit membrane-embedded enzyme accepts four electrons from cytochrome c and uses them to reduce 02 to 2 H20. It is also a proton pump. Its structure and functions are considered in Chapter 18. However, it is appropriate to mention here that the essential catalytic centers consist of two molecules of heme a (a and a3) and three Cu+ ions. In the fully oxidized enzyme two metal centers, one Cu2+ (of the two-copper center CuA) and one Fe3+ (heme a), can be detected by EPR spectroscopy. The other Cu2+ (CuB) and heme a3 exist as an EPR-silent exchange-coupled pair just as do the two copper ions of hemocyanin and of other type 3 binuclear copper centers. 

V. Darley-Usmar, D. Rickwood, and M. Wilson, Editors, Mitochondria A Practical Approach (1987), IRL Press (Oxford). An excellent source for laboratory techniques. R. Garrett and C. Grisham, Biochemistry, 2nd ed. (1999), W. B. Saunders (Orlando, FL), pp. 674-675. Mitochondrial structure and function. 

Subcellular Organelles. Toxic metals may disrupt the structure and function of a number of organelles. For example, enzymes associated with the endoplasmic reticulum may be inhibited, metals may be accumulated in the lysosomes, respiratory enzymes in the mitochondria may be inhibited, and metal inclusion bodies may be formed in the nucleus. 

An H+ electrochemical gradient (ApH+) provides the energy required for active transport of all classical neurotransmitters into synaptic vesicles. The Mg2+-dependent vacuolar-type H+-ATPase (V-ATPase) that produces this gradient resides on internal membranes of the secretory pathway, in particular endosomes and lysosomes (vacuole in yeast) as well as secretory vesicles (Figure 3). In terms of both structure and function, this pump resembles the F-type ATPases of bacteria, mitochondria and chloroplasts, and differs from the P-type ATPases expressed at the plasma membrane of mammalian cells (e.g., the Na+/K+-, gastric H+/K+-and muscle Ca2+-ATPases) (Forgac, 1989 Nelson, 1992). The vacuolar and F0F1... 

Other kinds of multiplicative mechanisms operate as a result of the structural and functional position of the receptor and event. Among the different macromolecules, attention has been focused on two kinds of receptors protein and lipid. The first as enzymes, and both as constituents of membranes, mitochondria, chloroplasts, or other cellular... 

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. 

Nass S (1969) The significance of the structural and functional similarities of bacteria and mitochondria. Int Rev Cytol 25 55-129... 

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