<prompt> Rough endoplasmic reticulum is the site of synthesis forProteinCholesterolCarbohydrateFat  <response>: Rough endoplasmic reticulum is concerned with Protein synthesisInitial folding of the polypeptide chains with the formation of disulfide bonds Smooth endoplasmic reticulum is concerned with Steroid synthesis Detoxication processes As sarcoplasmic reticulum plays important role in skeletal and cardiac muscle contraction 