fosforüülitamine

Fosforüülitamine, also known as phosphorylation, is a fundamental biochemical process in which a phosphate group (PO43-) is added to a molecule. This addition is typically catalyzed by enzymes called kinases. The phosphate group is usually transferred from a high-energy phosphate-donating molecule, most commonly adenosine triphosphate (ATP). Phosphorylation is a critical mechanism for regulating the activity of proteins, a key step in signal transduction pathways, and essential for energy storage and transfer within cells.

The addition of a phosphate group can significantly alter the three-dimensional structure and thus the function of a protein. This modification can activate or inactivate enzymes, change the binding affinity of proteins for other molecules, or trigger conformational changes that are part of cellular signaling cascades. In signal transduction, phosphorylation acts as a molecular switch, propagating signals from the cell surface to the interior, leading to specific cellular responses.

Beyond protein modification, phosphorylation is central to energy metabolism. The breakdown of ATP to ADP (adenosine diphosphate) and inorganic phosphate releases energy, which cells use to power various processes. Conversely, the synthesis of ATP from ADP and phosphate, often occurring during cellular respiration and photosynthesis, stores energy. Phosphorylation also plays roles in the synthesis and degradation of nucleic acids and in the regulation of gene expression. The reversibility of phosphorylation, often through the action of phosphatases which remove phosphate groups, allows for dynamic control of cellular processes.