Difference Between Pinocytosis and Receptor-Mediated Endocytosis

March 2022 · 5 minute read

There are two important forms of endocytosis called Pinocytosis, and the other is Receptor-Mediated Endocytosis. Pinocytosis is different, and it is not like receptor-mediated endocytosis as pinocytosis is non-specific when it comes to substances that are transported by them. The water absorption in pinocytosis takes place in small quantities than receptor-mediated endocytosis, and it will take the water in large quantities. 

Pinocytosis vs Receptor-Mediated Endocytosis

The main difference between Pinocytosis and Receptor-Mediated Endocytosis is in pinocytosis, the liquid will be ingested into the cell. In receptor-mediated endocytosis, the specific molecules will be ingested into the cell. The major difference is pinocytosis does not use selection, but receptor-mediated endocytosis uses selection. The efficiency of pinocytosis is less. However, the efficiency of receptor-mediated endocytosis is more.

Pinocytosis is called the ingestion of surrounding fluids. It is an active transport that plays a vital role in cellular processes such as waste materials excretion, uptaking of nutrients, and signal transduction. It plays an important role for higher organisms for transporting fats and vitamins in dissolved molecules. It is mostly seen in unicellular organisms like amoeba, which uses it for uptaking or water and dissolving nutrients. 

Receptor-mediated endocytosis is related to cholesterol as the cells in them will be taken up in the blood. It is one of the essential components of all cell membranes. The regulatory molecules in receptor-mediated endocytosis will bind to plasma membrane receptors which will target the cells. They use the same membranes for processing. Here, only specific molecules are ingested into the cell. 

Comparison Table Between Pinocytosis and Receptor-Mediated Endocytosis

Parameters of ComparisonPinocytosisReceptor-Mediated Endocytosis
ProcessIt is not a selective process.It is a selective process.
Process efficiencyIt is less efficient.It requires more efficiency.
ReceptorsIt does not involve receptors.It uses receptors on the cell membrane.
UptakesLiquidSolutes
Also called asCell drinkingClathrin-mediated endocytosis

What is Pinocytosis?

It is a process by which liquid droplets ingest the living cells. It is a type that comes under endocytosis. In endocytosis, the cellular substances are brought inside the cell. In pinocytosis, the cell membrane creates small packets by folding them and then captures the dissolved substances and cellular fluids. In pharmacology, the particles or fluid will be engulfed by the cell. Pinocytosis is otherwise called Fluid Endocytosis. 

In pinocytosis, an individual droplet of liquid will be passively traveled through the cell membrane. Then the droplet will be either absorbed or bound on the cell membrane. In most cells, it is formed as a continuous process. It is a non-specific way of internalizing dissolved nutrients. The process will be initiated with the help of the desired molecule in the extracellular fluid. The molecules can be of any form, such as proteins, sugars, ions, and other molecules.

It is different from another receptor-mediated endocytosis as it is not specific about one molecule. Pinocytosis is divided into two types called macropinocytosis and micropinocytosis. In macropinocytosis, the molecules are larger in size. In micropinocytosis, the molecules are smaller in size. They are divided based on molecule size. Because of its non-specific absorption of molecules, a large number of different molecules will be transported at the same time.  

What is Receptor-Mediated Endocytosis?

It is a form of endocytosis. It uptakes only solutes in the cells. One of the examples of receptor-mediated endocytosis is importing iron into a mammalian cell. Because iron has serum cholesterol which will not allow it to import by itself. The viruses in receptor-mediated endocytosis are well established because the internalization of viruses is only dependent on virus-specific surface cellular receptors. 

Also, the virus will attack the cells which display the specific receptors. With the help of receptors, they bind specific ligands. And these ligands are coated pits to form endosomes. It is active. It has a mechanism for selective uptake of specific macromolecules. All mammalian cells carry out receptor-mediated endocytosis at some level. Phagocytosis is formed from receptor-mediated endocytosis. Clathrin is involved in three receptor-mediated intracellular transport pathways.

Some risks may develop in receptor-mediated endocytosis that will lead to the development of proteinuria and loss of substances. It is one of the important signs of kidney disease. This will lead to cardiovascular disease as well. One of the advantages of receptor-mediated endocytosis is it allows the macromolecules to enter the cells which are needed for cellular function. Their mode of picking up the particles also varies on the extracellular space. 

Main Differences Between Pinocytosis and Receptor-Mediated Endocytosis

  • When it comes to process, pinocytosis is not selective. On the other hand, the process involved in receptor-mediated endocytosis is selective.
  • The process efficiency of pinocytosis is less efficient. On the other hand, the process efficiency of receptor-mediated endocytosis requires more efficiency. 
  • Pinocytosis does not use receptors. On the other hand, receptor-mediated endocytosis uses receptors that are available in the cell membrane.
  • Pinocytosis uptakes liquid. On the other hand, receptor-mediated endocytosis uptakes solutes.
  • Pinocytosis is also called cell drinking. On the other hand, the other name for receptor-mediated endocytosis is Clathrin-mediated endocytosis.
  • In pinocytosis, solutes in the extracellular fluid go into cells. On the other hand, in receptor-mediated endocytosis, the solutes will bind into the cell. 
  • Conclusion

    Both come under the type of endocytosis. They are responsible for taking liquids and solutes in the cell. They have a major difference when it comes to selection as pinocytosis does not require selection but receptor-mediated endocytosis required selection. However, receptor-mediated endocytosis is considered to be a complex process because of the macromolecules in it.

    These types of topics are dealt with in science. One should have taken science stream in their school and college to learn more about them and the way they work. Because in schools only a basic concept about them would have been taught. But in college, a vast area about them will be taken which will cover more advanced topics.

    References

  • https://europepmc.org/article/med/9174669
  • https://pubs.acs.org/doi/abs/10.1021/nn205125e
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