Localization of catalytic and regulatory subunits of cyclic AMP-dependent protein kinases in mitochondria from various rat tissues

Schwoch, G; Trinczek, Bernhard; Bode, Christa

doi:10.1042/bj2700181

Cited by 64 publications

(52 citation statements)

References 44 publications

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“…Activation of sAC would stimulate intramitochondrial protein kinase A (PKA) (Schwoch et al, 1990), which can phosphorylate many ETS proteins (Valsecchi et al, 2013), altering their activity (Lee et al, 2005;Tomitsuka et al, 2009;Phillips et al, 2012). Because sAC and PKA are temperature sensitive, such a mechanism could explain the pattern of mitochondrial suppression in hibernators, but to date no changes in the phosphorylation of mitochondrial proteins have been found among torpor bout phases, though seasonal differences are evident (Chung et al, 2013).…”

Section: A Role For Post-translational Modifications?mentioning

confidence: 99%

Metabolic suppression in mammalian hibernation: the role of mitochondria

Staples

2014

Journal of Experimental Biology

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Hibernation evolved in some small mammals that live in cold environments, presumably to conserve energy when food supplies are low. Throughout the winter, hibernators cycle spontaneously between torpor, with low metabolism and near-freezing body temperatures, and euthermia, with high metabolism and body temperatures near 37°C. Understanding the mechanisms underlying this natural model of extreme metabolic plasticity is important for fundamental and applied science. During entrance into torpor, reductions in metabolic rate begin before body temperatures fall, even when thermogenesis is not active, suggesting active mechanisms of metabolic suppression, rather than passive thermal effects. Mitochondrial respiration is suppressed during torpor, especially when measured in liver mitochondria fuelled with succinate at 37°C in vitro. This suppression of mitochondrial metabolism appears to be invoked quickly during entrance into torpor when body temperature is high, but is reversed slowly during arousal when body temperature is low. This pattern may reflect body temperaturesensitive, enzyme-mediated post-translational modifications of oxidative phosphorylation complexes, for instance by phosphorylation or acetylation.KEY WORDS: Heat, Body temperature, Thermoregulation, Thermogenesis, Oxidative phosphorylation, Post-translational modification, Acetylation, Phosphorylation IntroductionMost mammals are strict endotherms, i.e. they maintain fairly constant body temperatures (T b ) near 37°C using heat derived primarily from endogenous metabolism. In cold environments, mammals retain some of this heat by regulating insulation (using underfur and/or subcutaneous fat), peripheral blood circulation (using vasoconstriction and/or countercurrent heat exchangers) and ventilatory evaporation. At very cold temperatures, the high gradient between T b and ambient temperature (T a ) causes large heat loss by radiation and conduction, which is also affected by convection of water or air. For small mammals, the high body surface area, relative to volume, results in greater mass-specific rates of heat loss. While large land mammals can increase insulation by changing the quality (microstructure) and quantity (length, density) of underfur, this option is limited for small mammals. Imagine a 70 mm long lemming growing fur 100 mm long; it might stay warm, but when it tripped over that fur it would be easy prey.Despite the challenges, many small mammals thrive in cold environments. To compensate for high heat loss, these mammals upregulate their capacities to produce metabolic heat. Though COMMENTARY Department of Biology, University of Western Ontario, London, ON, Canada, N6A 5B8.*Author for correspondence (jfstaple@uwo.ca) effective, this strategy requires large quantities of fuel during winter when food availability is typically low. Many small mammals use stored food to power thermogenic metabolism. For example, American red squirrels (Tamiascurius hudsonicus) cache spruce cones and feed on the seeds throughout winter, allowing th...

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Section: A Role For Post-translational Modifications?mentioning

confidence: 99%

Metabolic suppression in mammalian hibernation: the role of mitochondria

Staples

2014

Journal of Experimental Biology

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“…Evidence for the existence of a mtPKA in mammalian [16][17][18] and yeast mitochondria [19] has also been presented by' others. Among the various proteins found to be phosphorylated by the mtPKA, 42 kDa and 16-18 kDa pro-…”

Section: Chemicalsmentioning

confidence: 99%

“…In the IM fraction of bovine-heart mitochondria, consisting essentially of scrambled inner membrane, cAMP induces phosphorylation by [y-3ZP]ATP of proteins of apparent Mr 29,18 and 6 kDa ( Fig. 1) (see also [14,15]).…”

Section: *Corresponding Author Institute Of Medical Biochemistry Andmentioning

confidence: 99%

Characterization of proteins phosphorylated by the cAMP‐dependent protein kinase of bovine heart mitochondria

et al. 1995

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Characterization of two mitochondrial proteins of M~ 42 and 18 kDa, respectively, phosphorylated by the cAMP-dependent protein kinase of bovine heart mitochondria (mtPKA), is presented. A 42 kDa protein is found to be loosely associated to complexes l, III and IV of the respiratory chain and complex V (ATP synthase) in the inner mitochondrial membrane. An 18 kDa protein is associated to complex I in tbe inner membrane and in a purified preparation of this complex where it can be phosphorylated by the isolated catalytic subunit of PKA.teins (apparent Mr depending on the electrophoretic procedure) were observed [14,15]. We have now found that an 18 kDa protein phosphorylated by mtPKA is associated with NADHubiquinone oxidoreductase (complex I) in the inner mitochondrial membrane and in its isolated preparation. Protein(s) of 42 kDa, phosphorylated by the mtPKA, is(are) also found to be loosely associated with complex I as well as with bc l complex, cytochrome c oxidase and ATP synthase (complexes III, IV and V) in the inner mitochondrial membrane.

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“…Recent work from our group has shown that in bovine heart mitochondria various proteins are phosphorylated by a cAMPdependent protein kinase (mtPKA) present in these organelles [7][8][9][10]. An mtPKA has also been detected in yeast mitochondria [1 1].…”

Section: Introductionmentioning

confidence: 99%

The nuclear‐encoded 18 kDa (IP) AQDQ subunit of bovine heart complex I is phosphorylated by the mitochondrial cAMP‐dependent protein kinase

et al. 1996

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In bovine heart mitochondria a protein of M, 18 kDa, phosphorylated by mtPKA, is associated to the NADH-ubiquinone oxidoreductase in the inner membrane and is present in purified preparation of this complex. The 18 kDa phosphoprotein has now been isolated and sequenced. It is identified as the 18 kDa (IP) AQDQ subnnit of complex I, a protein of 133 amino acids with a phospborylation consensus site RVS at position 129-131.

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Localization of catalytic and regulatory subunits of cyclic AMP-dependent protein kinases in mitochondria from various rat tissues

Cited by 64 publications

References 44 publications

Metabolic suppression in mammalian hibernation: the role of mitochondria

Metabolic suppression in mammalian hibernation: the role of mitochondria

Characterization of proteins phosphorylated by the cAMP‐dependent protein kinase of bovine heart mitochondria

The nuclear‐encoded 18 kDa (IP) AQDQ subunit of bovine heart complex I is phosphorylated by the mitochondrial cAMP‐dependent protein kinase

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