Glükoos6fosfaat

Glükoos6fosfaat, often abbreviated as G6P, is a vital molecule in cellular metabolism. It is the phosphorylated form of glucose, meaning a phosphate group is attached to the sixth carbon atom of the glucose molecule. This phosphorylation is the first step in glycolysis, the primary pathway for breaking down glucose to produce energy.

The formation of glucose-6-phosphate is catalyzed by enzymes called hexokinases (in most cells) or glucokinases (specifically in the liver and pancreas). This reaction traps glucose inside the cell, as the phosphate group prevents it from easily crossing the cell membrane. G6P can then enter various metabolic pathways.

In addition to glycolysis, glucose-6-phosphate is a key intermediate in the pentose phosphate pathway, which generates NADPH for reductive biosynthesis and provides precursors for nucleotide synthesis. It is also involved in glycogen synthesis and gluconeogenesis, the process of creating glucose from non-carbohydrate sources. The liver plays a crucial role in regulating blood glucose levels by interconverting glucose and glucose-6-phosphate. When blood glucose is high, the liver converts it to glycogen for storage, utilizing G6P. When blood glucose is low, the liver breaks down glycogen, releasing glucose which is then dephosphorylated from G6P before entering the bloodstream.