What are the main processes of the ER?

There are multiple processes that occur in the ER (endoplasmic reticulum). The specific processes that occur differ depending on the type of ER.

Production and synthesis of proteins are the main processes that occur in the rough ER. The protein-building material from the DNA in the cell’s nucleus is transferred to the ribosomes on the rough ER’s membrane where they are then translated into strings of amino acids. Protein sorting and folding, which are crucial processes for efficient cellular function, occur in the interior lumen of the rough ER.

Biosynthesis of lipids such as phospholipids, fatty acids, and cholesterol molecules is the main process that occurs in the smooth ER. Production of lipid hormones and maintenance of calcium homeostasis also occur in the smooth ER. Metabolism and detoxification occur in the smooth ER in liver cells.