RER Full Form

The endoplasmic reticulum (ER) is the eukaryotic cell’s transportation system, as well as a host of other activities such as protein folding. Rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum (SER) are two subunits of this type of organelle (SER). Most eukaryotic cells have an endoplasmic reticulum, which is a network of flattened, membrane-enclosed sacs known as cisternae (in the RER) and tubular structures (in the SER). The ER membranes are connected to the outer nuclear membrane. Red blood cells and spermatozoa do not contain the endoplasmic reticulum.

Many of the proteins found in both forms of ER are the same, and they perform similar functions such as lipid and cholesterol production. Depending on the cell’s activity, different types of cells have varied ratios of the two types of ER. RER is mostly located in the cell nucleus, while SER is mostly found in the cell membrane or plasma membrane.

Endoplasmic Reticulum

There are two types of endoplasmic reticulum: one with a ribosome-studded surface and the other with a smooth surface. The smooth endoplasmic reticulum is the latter, while the rough endoplasmic reticulum is the former. These membranes fold continuously, finally joining the nuclear membrane’s outer layer. The endoplasmic reticulum is found in every type of eukaryotic cell except sperm cells and red blood cells.

Endoplasmic Reticulum Structure

The endoplasmic reticulum (ER) has a sac-like structure. Because there are two sorts of ER, each has its unique set of characteristics:

Endoplasmic Reticulum Rough Structure

• The rough endoplasmic reticulum gets its name from the way it looks.
• The term comes from a network of connected flattened sacs with many ribosomes on their outer surface.
• It produces and secretes proteins, hormones, and other chemicals in the liver and glands.
• In cells where protein synthesis occurs, rough ER is prevalent (such as hepatocytes).

Endoplasmic Reticulum Smooth Structure

• Ribosomes, on the other hand, are absent from the smooth endoplasmic reticulum.
• The tubular shape of the smooth endoplasmic reticulum.
• It takes part in the formation of phospholipids, which are the main lipids in cell membranes and are required for metabolism.
• The rough ER’s products are transported to other cellul ar organelles, particularly the Golgi apparatus, by the smooth ER.

Rough Endoplasmic Reticulum

The rough endoplasmic reticulum (also known as granular endoplasmic reticulum) is studded with protein-producing ribosomes, giving it a “rough” appearance (hence its name).The translocon is the ribosome’s binding location on the rough endoplasmic reticulum. However, because ribosomes are continually bound and released from the membrane, they are not a stable element of this organelle’s structure. Only once a particular protein-nucleic acid combination occurs in the cytoplasm does a ribosome bind to the RER. When a free ribosome starts translating the mRNA of a protein bound for the secretory route, this unique complex arises. A signal peptide, a chemical communication that is detected and bound by a signal recognition particle, is encoded by the first 5–30 amino acids polymerized (SRP). The ribosome complex binds to the RER translocon, which resumes translation with the nascent (new) protein developing in the RER lumen and/or membrane. A signal peptidase enzyme processes the protein in the ER lumen, removing the signal peptide. Ribosomes may be discharged into the cytosol at this point, however non-translating ribosomes are known to remain connected with translocons.

Multiple Functions Rely on the Rough Endoplasmic Reticulum

• Lysosomal enzyme production with a mannose-6-phosphate marker in the cis-Golgi network.
• Secreted protein production, either constitutively with no tag or in a regulated manner involving clathrin and paired basic amino acids in the signal peptide.
• As vesicles escape and bind to new membranes, integral membrane proteins remain lodged in the membrane. Rab proteins are important for membrane targeting, while SNAP and SNARE proteins are important for fusion.
• Assemblies proceed, glycosylation begins. It’s N-linked (O-linking occurs in the Golgi).
• If the protein is appropriately folded, oligosaccharyltransferase recognises the AA sequence NXS or NXT (with the S/T residue phosphorylated) and adds a 14-sugar backbone to the side-chain nitrogen of Asn (2-N-acetylglucosamine, 9-branching mannose, and 3-glucose at the end).

Conclusion

The endoplasmic reticulum is a membrane organelle that runs parallel to the nuclear envelope in eukaryotic cells. Smooth endoplasmic reticulum and rough endoplasmic reticulum are the two types. What gives the rough endoplasmic reticulum its rough appearance? The presence of ribosomes on the surface is the answer. Ribosomes are found on the surface of the rough endoplasmic reticulum, but not the smooth endoplasmic reticulum. Ribosomes, which are made up of ribosomal RNA and protein, are another type of organelle. Protein production is their primary function in the cell. Ribosomes can be present in the cytoplasm or on the RER. Rough and smooth endoplasmic reticulum portions are usually found in cells. Only highly specialised cells, on the other hand, have large portions of smooth endoplasmic reticulum.