cytosol

Friday, February 6, 2009

The cytosol is the liquid found inside cells. It is the gel-like "soup" within which all the other cell organelles reside and where most of the cellular metabolism occurs. Though mostly water, the cytosol is full of proteins that control cell metabolism including signal transduction pathways, glycolysis, intracellular receptors, and transcription factors. Cytoplasm is a collective term for the cytosol plus the organelles suspended within the cytosol.

The term cytosol is used to refer to the liquid phase of the cytoplasm in an intact cell, this excludes any part of the cytoplasm that is contained within organelles. The cytosol consists mostly of water, dissolved ions, small molecules, and large water-soluble molecules, such as proteins. In contrast to extracellular fluid, cytosol has a high concentration of potassium ions and a low concentration of sodium ions.