Functions of smooth endoplasmic reticulum
Smooth ER synthesizes fats and lipids.
It also takes part in the metabolism of carbohydrates.
It actively participates in drug detoxification.
It maintains the calcium ion concentration in the cytosol.
Functions of rough endoplasmic reticulum
Most of the lysosomal proteins are produced in the rough ER.
It transports proteins to various destinations like the plasma membrane.
This is the major site of glycosylation (addition of carbohydrates in proteins).