![]() ![]() In the first phase, glucose is phosphorylated at the hydroxyl group on C-6 by hexokinase (HK) generating glucose 6-phosphate. Hypothetical contacts between ATP storage vesicles and mitochondria, with preferential ATP transfer, are shown within the red dotted circle Reduction of pyruvate to lactate is represented inside the red dotted rectangle. Glycolysis is represented in the yellow and blue boxes, the TCA cycle by the green circle, and oxidative phosphorylation in the orange box. Schematic representation of mechanisms of ATP synthesis and storage inside the cell. Metabolic alterations that promote the sustaining of cancer progression, as well as methods for monitoring ATP levels and production are also reviewed here.ĪTP management within the cell. The aim of this work is to provide an overview of the principles governing ATP production and describe cellular mechanisms that sense levels of ATP and regulate its synthesis. In addition, it should be mentioned that acetyl-CoA can be generated also by lipid and protein catabolism. Finally, NADH is used by the respiratory chain complexes to generate a proton gradient across the inner mitochondrial membrane, necessary for the production of large amounts of ATP by mitochondrial ATP synthase. Subsequently, pyruvate is converted to acetyl coenzyme A (acetyl-CoA) which enters the TCA cycle, enabling the production of NADH. In the first process, when glucose is converted into pyruvate, the amount of ATP produced is low. In general, the main energy source for cellular metabolism is glucose, which is catabolized in the three subsequent processes-glycolysis, tricarboxylic acid cycle (TCA or Krebs cycle), and finally oxidative phosphorylation-to produce ATP. Among them, ATP is the effective central link-the exchange coin-between energy-producing and the energy-demanding processes that effectively involve formation, hydrolysis, or transfer of the terminal phosphate group. The oxidation process results in free energy production that can be stored in phosphoanhydrine “high-energy bonds” within molecules such as nucleoside diphosphate and nucleoside triphosphate (i.e., adenosine 5′ diphosphate and adenosine 5′ trisphosphate, ADP, and ATP, respectively), phosphoenolpyruvate, carbamoyl phosphate, 2,3-bisphosphoglycerate, and other phosphagens like phosphoarginine, or phosphocreatine. It is then used to sustain energy-dependent processes, such as the synthesis of macromolecules, muscle contraction, active ion transport, or thermogenesis. Within cells, energy is provided by oxidation of “metabolic fuels” such as carbohydrates, lipids, and proteins. Recent advances regarding ATP storage and its special significance for purinergic signalling will also be reviewed. In this review, we will discuss all the main mechanisms of ATP production linked to ADP phosphorylation as well the regulation of these mechanisms during stress conditions and in connection with calcium signalling events. It is also a signalling molecule in the purinergic signalling mechanisms. ATP is universally seen as the energy exchange factor that connects anabolism and catabolism but also fuels processes such as motile contraction, phosphorylations, and active transport. It is important to understand the concepts of glucose and oxygen consumption in aerobic and anaerobic life and to link bioenergetics with the vast amount of reactions occurring within cells. Many aspects of cell metabolism revolve around ATP production and consumption. Since 1929, when it was discovered that ATP is a substrate for muscle contraction, the knowledge about this purine nucleotide has been greatly expanded. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |