Endoplasmic reticulum (ER)

This overview addresses endoplasmic ER with particular emphasis on key features of the endoplasmic reticulum, including its structure and the distinction between rough and smooth ER. We will examine how the ER supports protein and lipid synthesis, protein quality control, and calcium regulation within eukaryotic cells. Additionally, we will discuss its role in detoxification, its communication with other organelles, and the consequences of ER dysfunction for cellular health and disease. We will explore the endoplasmic reticulum or ER, a central organelle in eukaryotic cells with diverse and essential functions. The ER forms a vast network of flattened sacs and tubules called cisternae held by the cytoskeleton. This membrane system is continuous with the outer nuclear envelope and extends through the cytoplasm. There are two main forms, rough ER with ribosomes attached for a rough appearance and smooth ER which lacks ribosomes. The ER's internal space called the lumen is crucial for many cellular processes. The rough ER is characterized by its ribosomes, which synthesize proteins destined for the secretary pathway. As translation begins, ribosomes attach to the ER membrane, allowing new polypeptides to enter the ER lumen or membrane, where they undergo folding, assembly, disulfide bonding, and glycosylation. Quality control is enforced by chaperones like BIP, calnexin and calaticulin.