Sitozol

Sitozol, known in English as cytosol, is the liquid component of the cytoplasm that fills the interior of the cell outside of organelles. It is the aqueous medium in which many metabolic reactions take place and in which soluble proteins, enzymes, and small metabolites are dissolved. The cytosol is largely water, but it also contains dissolved ions such as potassium, magnesium, and phosphate, as well as a wide range of metabolites and macromolecules. The environment is highly crowded by macromolecules, which affects reaction rates and diffusion.

Many essential cytosolic processes occur in the cytosol, including portions of glycolysis, protein synthesis on free ribosomes, and various signaling pathways. The cytosol also serves as a medium for the transport of small molecules between organelles and the plasma membrane. It provides a scaffold for enzymes and holds soluble components that participate in regulation and metabolism.

The cytoskeleton, a network of actin filaments, intermediate filaments, and microtubules, resides within the cytosol and organizes the cell’s shape, mechanics, and transport. The cytosol and cytosol-associated processes interact with organelles through transport systems and signaling networks, allowing exchange of nutrients and regulatory molecules.

In contrast to the broader term cytoplasm, which encompasses the cytosol plus organelles and inclusions, the cytosol specifically refers to the fluid component. Understanding the cytosol is important in cell biology, biochemistry, and physiology across organisms.