Cytosol

Definition

The aqueous, gel-like matrix of the cytoplasm, exclusive of membrane-bound organelles, containing dissolved ions, metabolites, proteins, and the cytoskeleton. In arthropod cells, the cytosol serves as the site of glycolysis, protein synthesis, and sequestration of metabolic intermediates such as trehalose and proline that fuel flight muscle activity in insects.

Etymology

From cyto- (cell) + -sol (solution), coined in cell biology to distinguish the soluble phase from the entire cytoplasm.

Example

In the fat body cells of a migratory locust, the cytosol accumulates high concentrations of ketone bodies and lipoproteins during fasting, mobilizing energy reserves for sustained flight.

Synonyms

• cytoplasmic matrix
• groundplasm

Related Terms

• Cytoplasm
• cytoskeleton
• mitochondrial matrix
• Hemolymph
• Fat body
• Trehalose

Usage Notes

Specialists distinguish cytosol (the soluble, non-organelle fraction) from cytoplasm (cytosol plus organelles). In arthropod physiology, cytosolic enzymes such as lactate dehydrogenase are often assayed in homogenates to assess metabolic stress. The term is sometimes used loosely in older literature to mean entire cytoplasm.