Rough ER Vs Smooth ER- Definition, 13 Differences, Examples

Rough ER Vs Smooth ER- Definition

Rough Endoplasmic Reticulum (RER)

  • One kind of endoplasmic reticulum, known as the rough endoplasmic reticulum, is made up of flattened sacs with ribosomes on the exterior.
  • The endomembrane system, which is located with in the cell’s cytoplasm, includes the rough endoplasmic reticulum.
  • This organelle is involved in protein synthesis, folding, alteration, as well as distribution to other organelles inside and beyond the cell.
  • The term “rough” ER refers to how ribosomes under a microscope, the ER’s surface resembles studs.
  • The RER membrane is continuous with the nuclear membrane and is present in both plant and animal cells.
  • The RER is often found close to the Golgi apparatus, and the vesicles that contain the protein that was created in the ribosomes there are then transferred to the Golgi body.
  • With few tubules, rough ER is mostly composed of flattened sacs termed cisternae. A crucial protein complex called translocon is also present in the membrane and is needed for RER translation.
  • With the aid of the ribophorin protein family, the ribosomes are joined to the endoplasmic reticulum.
  • Rough ER is predicated on the existence of cytoskeletal components like microtubules, and modifications to microtubules result in modifications to RER.
  • Additionally, the ribosomes seen on the rough ER often separate and form distinct cisternae.
  • Newly produced proteins go through minor changes in the RER lumen, including as the breakage of signal sequences and glycosylation. Several proteins might modify their three-dimensional shape inside the lumen.
  • Lysosome development is highly correlated with rough ER.
  • Additionally, Rough ER is essential for the quality control of protein folding,where an increase in the amount of unfolded proteins in the cell alters the proportion of sheets to tubules.
  • Occasionally, an increase in the number of unfolded proteins initiates apoptosis in a cell.
  • Similar to this, rough ER also has several RNA metabolism-related enzymes that bind to and alter RNA.
  • However, the misfolding of proteins in RER may lead to several illnesses. Spondyloepimetaphyseal dysplasia, for example, is related to the buildup of improperly folded collagen proteins in the RER.

Smooth Endoplasmic Reticulum (SER)

  • The production and storage of lipids take place in the smooth endoplasmic reticulum (SER), a kind of endoplasmic reticulum composed of tubular vesicles without an outer ribosome membrane.
  • The endomembrane system includes the smooth ER, which generates important structural lipids such as cholesterol and phospholipids.
  • The word “smooth” denotes a smooth outer surface since there are no ribosomes present there.
  • After the surface’s current ribosomes are lost, rough ER is converted into smooth ER.
  • Rough and smooth ER are both present in both plants and animals. human liver cells that synthesise steroid hormones include a high concentration of smooth ER.
  • The major component of the smooth endoplasmic reticulum is a network of tubules. It is mostly located near the cell membrane.
  • These structures are often linked to the development of oleosomes or spherosomes.
  • Human muscle as well as nerve cells, which create links between other cells,  have a notable tubular smooth ER structure.
  • The smooth ER that make up the sarcoplasmic reticulum in muscle cells play a crucial role in the calcium ion accumulation process.
  • Additionally, the dynamic nature of the smooth ER emits new tubules from the sidewalls. Additionally, these tubules are linked to the cell’s cytoskeletal structure.
  • The kind, location, and purpose of the cell all affect how many smooth ER are present. Muscle and glandular cells have a considerably smaller amount of SER.
  • In the endocrine system, the smooth ER is also responsible for producing steroid hormones from cholesterol.
  • It generates enzymes with in liver which catalyse drug elimination processes,metabolic waste, and dangerous chemical compounds. Because of its dynamic nature, SER may amass a lot of dangerous compounds during detoxifying.
  • The detoxification of toxins and the elimination of wastes depend on SER.
  • Additionally, the smooth ER contains the enzyme glucose-6-phosphate, that is essential for the conversion of glycogen to glucose.
  • The development and progression of several diseases, such as neurodegeneration, atherosclerosis, type 2 diabetes, liver disease, as well as even cancer,might occur as a consequence of persistent SER stress, however.

Key Differences (Rough endoplasmic reticulum vs Smooth endoplasmic reticulum)

Basis for comparison Rough endoplasmic reticulum (RER) Smooth endoplasmic reticulum (SER)
Definition The rough endoplasmic reticulum is a type of endoplasmic reticulum consisting of flattened sacs, studded with protein-synthesizing particles termed ribosomes on the outer surface. Smooth endoplasmic reticulum (SER) is a type of endoplasmic reticulum consisting of tubular vesicles that lack ribosomes on the outer surface and is involved in the synthesis and storage of lipids.
Ribosomes Rough ER has ribosomes on the outer surface. Smooth ER doesn’ thave ribosomes on the outer surface.
Location The rough endoplasmic reticulum is mostly found around the nuclear membrane. The smooth endoplasmic reticulum is mostly found near the cell membrane.
Origin Rough ER is formed from the nuclear membrane. Smooth ER is formed after the shedding of ribosomes from rough ER.
Structure Rough ER is mainly composed of cisternae with few tubules. Smooth ER is mainly composed of a network of tubules with few cisternae.
Rough ER posses narrow pores below the ribosomes that allow the passage of newly synthesized polypeptides to the cytosol. No such pores are present on the surface of the smooth ER.
Ribophorins Ribophorins are present on the surface of the rough ER. Ribophorins are absent on the surface of the smooth ER.
Involved in Rough ERs are involved in the formation of lysosomes. Smooth ERs are involved in the formation of spherosomes or oleosomes.
Found in Numerous rough ER is found in lipid synthesizing cells. Numerous smooth ER is found in protein synthesizing cells.
Type of cell RER is mostly found in cells of glands and protein-producing organs. SER is mostly found in cells like muscle cells and nerve cells.
Golgi apparatus Rough ER provides proteins and lipids for the Golgi apparatus. Smooth ER provides vesicles for the cis-face of the Golgi apparatus.
Function The rough endoplasmic reticulum is mostly associated with the production, modification, and transfer of proteins. The smooth endoplasmic reticulum is mostly associated with the production of lipids and the storage of calcium ions.
Diseases Disease like spondyloepimetaphyseal dysplasia is attributed due to the accumulation of misfolded collagen proteins in the RER. Prolonged SER stress might result in the development and progression of many diseases, including neurodegeneration, atherosclerosis, type 2 diabetes, liver disease, and even cancer.

References and Sources

  • Ozcan, L., & Tabas, I. (2012). Role of endoplasmic reticulum stress in metabolic disease and other disorders. Annual review of medicine, 63, 317–328. https://doi.org/10.1146/annurev-med-043010-144749
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