The rough endoplasmic reticulum (RER) is associated with:
Rough endoplasmic reticulum is morphologically distinguished by dense coating of electron-dense particles corresponding to ribosomes engaged in protein synthesis, conferring basophilia in light microscopy due to high RNA content. These bound ribosomes translate mRNAs encoding proteins bearing N-terminal hydrophobic signal peptides that target co-translationally to Sec61 translocon, threading nascent chain into lumen where signal peptidase cleaves signal and chaperones like BiP, calnexin, calreticulin and PDI assist oxidative folding and initial N-glycosylation. Typical cargos include secreted
Ref: Alberts et al., Molecular Biology of the Cell, 6th ed., Chapter 12: Rough ER in Secretory Protein Synthesis.