rER

• Rough endoplasmic reticulum  have ribosome's attached to them
  
• RER can occupy up to 90% of the cytoplasm
  
• RER covers a very large part of the cytoplasm with an extensive  membrane network
  
• RER isolates and   transports newly synthesised protein
  
• After the protein synthesis the RER moves and passes through the ER lumen.