Protein folding rough endoplasmic reticulum

The endoplasmic reticulum (ER) is folded and provides a large surface area. It is the roadway of the cell and allows for transport of materials through and out of the cell. There are two types of ER. Smooth endoplasmic reticulum contains no ribosomes on their surface. This is the site of lipid synthesis. Rough endoplasmic reticulum has ribosomes on their surface. They aid in the synthesis of proteins that are membrane bound or destined for secretion. 

---