The main difference between pinocytosis and receptor mediated endocytosis is that pinocytosis is a not a selective process while receptor-mediated endocytosis is a selective process. Furthermore, pinocytosis occurs simply through the cell membrane while receptor-mediated endocytosis occurs with the assistant of receptors.
Phagocytosis, pinocytosis and receptor-mediated endocytosis are the three methods of endocytosis, which is the process of taking materials into the cell by forming vesicles. Another name for pinocytosis is ‘cell drinking’ while receptor-mediated endocytosis is known as clathrin-mediated endocytosis as well.
Key Areas Covered
1. What is Pinocytosis
– Definition, Process, Importance
2. What is Receptor Mediated Endocytosis
– Definition, Process, Importance
3. What are the Similarities Between Pinocytosis and Receptor Mediated Endocytosis
– Outline of Common Features
4. What is the Difference Between Pinocytosis and Receptor Mediated Endocytosis
– Comparison of Key Differences
Key Terms
Clathrin, Endocytosis, Pinocytosis, Receptor Mediated Endocytosis, Selectivity
What is Pinocytosis
Pinocytosis is a simple method of endocytosis responsible for uptaking liquids into the cell along with their solutes. Therefore, it is also known as ‘cell drinking’. In cell drinking, the plasma membrane of the cell surrounds the liquids, forming a vesicle called pinosome as an invagination, and pinch off it into the cytoplasm.
Figure 1: Pinocytosis
Moreover, the liquid inside the vesicle get absorbed into the cytoplasm. Then, the remaining vesicle with solutes fuses with a lysosome whose digestive enzymes degrade its content. However, pinocytosis has a high demand for energy in the form of ATP when compared to phagocytosis, which is another method of endocytosis.
What is Receptor-Mediated Endocytosis
Receptor-mediated endocytosis (RME) is another method of endocytosis responsible for the uptake of solutes into the cell selectively. In this method, the receptors involve in selecting the molecules. After recognizing a specific solute like a nutrient or protein, a large protein molecule called clathrin is responsible for the formation of a pit in the inner plasma membrane. Then, this pit buds into a coated vesicle in the cytoplasm.
The main importance of this process is that it only allows a small portion of liquid to enter the cell. Also, due to the involvement of clathrin in the process, this type of endocytosis is also called clathrin-mediated endocytosis.
Figure 2: Receptor Mediated Endocytosis
In a general sense, receptor-mediated endocytosis is the main method of endocytosis in most types of cells. Some important types of molecules taken up into the cell by this process are hormone-binding molecules, iron-binding proteins like transferrin, low-density lipoprotein cholesterol carriers, etc.
Similarities Between Pinocytosis and Receptor Mediated Endocytosis
- Phagocytosis, pinocytosis and receptor-mediated endocytosis are the three methods of endocytosis.
- All of them use the cell membrane for the process.
- Also, both methods are important in the uptake of proteins and other substances that cannot easily diffuse into the cell through the plasma membrane.
- However, these methods have a high demand for cellular energy and they are categorized under active transport methods.
Difference Between Pinocytosis and Receptor Mediated Endocytosis
Definition
Pinocytosis refers to the ingestion of liquid into a cell by the budding of small vesicles from the cell membrane while receptor-mediated endocytosis refers to an endocytotic mechanism in which specific molecules are ingested into the cell. Thus, this is the main difference between pinocytosis and receptor mediated endocytosis.
Also Called as
Moreover, pinocytosis is also called cell drinking while receptor-mediated endocytosis is also called clathrin-mediated endocytosis.
Main Components to be Uptaken
Furthermore, pinocytosis mainly uptakes liquids while receptor-mediated endocytosis mainly uptakes solutes.
Receptor Involvement
Another difference between pinocytosis and receptor mediated endocytosis is that the receptors do not involve in pinocytosis while the receptors on the cell membrane do involve in receptor-mediated endocytosis.
Selectivity
Also, selectivity is a major difference between pinocytosis and receptor mediated endocytosis. Pinocytosis is not a selective process while receptor-mediated endocytosis is a selective process.
Solute Intake
Besides, solutes in the extracellular fluid enter into the cell through pinocytosis while selected solutes bind to the receptors and enter the cell during receptor-mediated endocytosis.
Vesicle Formation
Vesicles form through the invagination of the plasma membrane in pinocytosis while vesicles form through the internal budding of the plasma membrane in receptor-mediated endocytosis. Hence, this is also a difference between pinocytosis and receptor mediated endocytosis.
Efficiency
Pinocytosis is a less efficient process while receptor-mediated endocytosis is an efficient process. This is another difference between pinocytosis and receptor mediated endocytosis.
Conclusion
Pinocytosis is a type of endocytosis responsible for the uptake of liquids into the cell. Also, it is not a selective process. Hence, different types of solutes can enter the cell along with the liquids. However, receptor-mediated endocytosis uses receptors to select molecules needed to be uptaken into the cell. Therefore, it is an efficient method of endocytosis. Thus, the main difference between pinocytosis and receptor mediated endocytosis is their selectivity.
References:
1. Bailey, Regina. “All About Pinocytosis and Cell Drinking.” ThoughtCo, Oct. 19, 2018, Available Here
Image Courtesy:
1. “Pinocytosis” By Jacek FH – modified Image:Endocytosis types.svg, author Mariana Ruiz Villarreal LadyofHats (Public Domain) via Commons Wikimedia
2. “0309 RME” By OpenStax – from the TextbookOpenStax Anatomy and PhysiologyPublished May 18, 2016 (CC BY 3.0) via Commons Wikimedia
Leave a Reply