What does cytosolic mean?
Cytosolic is an adjective from cell biology that describes anything situated in, or pertaining to, the cytosol — the watery, gel-like fluid that fills a cell's interior and surrounds its organelles. The cytosol makes up the largest part of the cytoplasm, and it is where many essential processes unfold: protein synthesis on free ribosomes, glycolysis, and the transmission of chemical signals all occur largely in this compartment. Scientists therefore speak routinely of cytosolic enzymes, cytosolic proteins, and cytosolic concentrations of ions such as calcium. The term is precise by design: because the cytoplasm includes both the organelles and the fluid around them, calling something cytosolic signals that it lies free in solution rather than inside a membrane-bound structure. It appears almost entirely in scientific writing — research papers, textbooks, and laboratory reports — and carries a neutral, technical connotation with no figurative or everyday use. For students of biology or medicine, it is a small but indispensable piece of vocabulary for describing exactly where in the cell a molecule resides.
adjectiveRelating to or located in the cytosol, the fluid portion of the cytoplasm in which the organelles of a cell are suspended.
- Of, relating to, or contained within the cytosol — the aqueous component of the cytoplasm of a cell, excluding organelles.
"The enzyme remains cytosolic until calcium signaling triggers its translocation to the cell membrane."
"Cytosolic proteins are synthesized on free ribosomes rather than on the rough endoplasmic reticulum."
"Researchers measured a rapid rise in cytosolic calcium following receptor activation."
Every living cell keeps most of its chemistry dissolved in one fluid — and 'cytosolic' is the word scientists use for anything floating in it.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of cytosolic
Cytosolic combines two Greek roots: kyto-, meaning 'cell' or 'hollow vessel', and sol(utio), ultimately from Latin solvere, meaning 'to dissolve', reflecting the fact that the cytosol is the dissolved phase of the cytoplasm. The underlying noun cytosol was coined during the twentieth century as cell biologists distinguished the fluid matrix of the cytoplasm from its organelles, and the adjective cytosolic followed naturally. Its relatives include cytology, cytoplasm, and cytoskeleton, all built on the same Greek root for cell.
How cytosolic is actually used
A technical term used almost exclusively in cell biology, biochemistry, and related scientific fields; it is rarely encountered outside academic literature. It is typically applied to enzymes, proteins, ions, and other molecules found free in solution within the cell.
Easily confused with cytosolic
Cytoplasmic refers broadly to everything within the cell's cytoplasm, while cytosolic specifically denotes the fluid (cytosol) surrounding the organelles.