Zymosterol is an intermediate in
cholesterol
Cholesterol is any of a class of certain organic molecules called lipids. It is a sterol (or modified steroid), a type of lipid. Cholesterol is biosynthesized by all animal cells and is an essential structural component of animal cell mem ...
biosynthesis. Disregarding some intermediate compounds (e.g. 4-4-dimethylzymosterol)
lanosterol
Lanosterol is a tetracyclic triterpenoid and is the compound from which all animal and fungal steroids are derived. By contrast plant steroids are produced via cycloartenol.
Role in biosynthesis of other steroids
Elaboration of lanosterol under e ...
can be considered a precursor of zymosterol in the cholesterol synthesis pathway. The conversion of zymosterol into cholesterol happens in the
endoplasmic reticulum
The endoplasmic reticulum (ER) is, in essence, the transportation system of the eukaryotic cell, and has many other important functions such as protein folding. It is a type of organelle made up of two subunits – rough endoplasmic reticulum ( ...
. Zymosterol accumulates quickly in the plasma membrane coming from the
cytosol
The cytosol, also known as cytoplasmic matrix or groundplasm, is one of the liquids found inside cells (intracellular fluid (ICF)). It is separated into compartments by membranes. For example, the mitochondrial matrix separates the mitochondri ...
. The movement of zymosterol across the cytosol is more than twice as fast as the movement of cholesterol itself.
{{Cholesterol and steroid intermediates
Cholestanes
Sterols