What type of phosphorylation is performed by 3-phosphoglycerate kinase?

3-phosphoglycerate kinase performs substrate-level phosphorylation, which is a process where a phosphate group is directly transferred from a donor molecule to ADP to form ATP. This occurs during specific metabolic pathways, particularly glycolysis, where 3-phosphoglycerate is converted into another molecule while simultaneously phosphorylating ADP.

In substrate-level phosphorylation, the energy for ATP production comes directly from the chemical reaction rather than through the electron transport chain or proton gradient, which is characteristic of oxidative phosphorylation. This makes it distinct from oxidative phosphorylation, which occurs in the mitochondria and relies on high-energy electron carriers.

Photophosphorylation occurs in photosynthetic organisms as part of the light-dependent reactions, where light energy is used to add a phosphate group to ADP, a mechanism that is also distinct from that of 3-phosphoglycerate kinase. Fermentation is an anaerobic process that generates ATP without using oxygen or the electron transport chain, and it does not involve the substrate-level phosphorylation that 3-phosphoglycerate kinase performs.

Understanding the function of 3-phosphoglycerate kinase in glycolysis and its role in substrate-level phosphorylation is crucial for grasping the fundamental concepts in metabolic processes.