Zymosterol is an intermediate in
cholesterol biosynthesis. Disregarding some intermediate compounds (e.g. 4-4-dimethylzymosterol)
lanosterol 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 mitochond ...
. 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