Functions of Smooth ER Appears smooth in the electron microscope because its cytoplasmic surface lacks ribosomes. For example, mammalian sex hormones and steroids secreted by the adrenal gland. Participates in carbohydrate metabolism. Detoxifies drugs and poisons. Smooth ER, especially in the liver, contains enzymes which detoxify drugs and poisons.
Enzymes catalyze the addition of hydroxyl groups to drugs and poisons.
This makes them soluble in the cytosol, so they may be excreted from the body. Smooth ER in liver cells proliferates in response to barbiturates, alcohol and other drugs. This, in turn, may increase drug tolerance. Stores calcium ions necessary for muscle contraction. Manufactures secretory proteins and membrane.