The key difference between cytosol and s9 fraction is that cytosol is a liquid phase which comprises of structural components of a cell apart from the nucleus while s9 fraction is the supernatant fraction obtained from an organ homogenate by the low-speed centrifugation in a suitable medium.
Cytosol and S9 fraction are two components related to cells. The cytosol is the fluid in which the cell organelles are suspended. In simple words, it is the liquid phase found inside the plasma membrane of a cell. S9 fraction is the supernatant obtained from the low-speed centrifugation of a tissue or organ homogenate. It is useful in biological assays in order to measure the metabolism of drugs and other xenobiotics.
CONTENTS
1. Overview and Key Difference
2. What is Cytosol
3. What is S9 Fraction
4. Similarities Between Cytosol and S9 Fraction
5. Side by Side Comparison – Cytosol vs S9 Fraction in Tabular Form
6. Summary
What is Cytosol?
Cytosol is a semi-solid, nutrient-rich complex medium that provides surface area for the cellular organelles and other cellular structures except for the cell nucleus. The outer boundary of the cytosol is the plasma membrane. The cytosol is rich in components such as proteins, carbohydrates, globular structures, ions, vitamins, and minerals. The main constituent present in the cytosol is water.
Figure 01: Cytosol
Cytosol is very rich in proteins as all synthesized proteins are present in the cytosol following translation. Furthermore, the cytosol regulates the osmotic balance of the cell and assists it to remain viable. Cytosol also aids in the locomotive function of the cell. All the major metabolic processes of the cell take place in the cytosol; therefore, the cytosol is the functionally active part of the cell.
What is S9 Fraction?
S9 fraction is the supernatant fraction obtained from the first low-speed centrifugation of the tissue homogenate. In simple words, it is the product of an organ tissue homogenate centrifuged at 9000 g for 20 minutes. This S9 fraction contains both cytosol (containing soluble proteins) and microsomes (membrane proteins). Usually, it is used to assess the metabolism of drugs and other xenobiotics. It is also used for biological assays. Moreover, S9 fraction is often added to the Ames test to assess the mutagenic potential of chemical compounds.
Figure 02: S9 Fraction
The preparation of S9 fraction is easy and it is achieved by first low-speed centrifugation of the tissue homogenate. By doing the second high-speed centrifugation, the cytosol can be separated from the microsomes.
What are the Similarities Between Cytosol and S9 Fraction?
- Cytosol is a part of the S9 fraction.
- Cytosol can be separated from the S9 fraction by second high-speed centrifugation.
- They contain soluble proteins.
What is the Difference Between Cytosol and S9 Fraction?
Cytosol is a liquid phase which comprises of structural components of a cell apart from the nucleus. In contrast, S9 fraction is the supernatant obtained from the tissue homogenate by low-speed centrifugation. Thus, this is the key difference between cytosol and S9 fraction. Moreover, cytosol contains proteins, carbohydrates, globular structures, ions, vitamins, and minerals while S9 fraction contains both cytosol and microsomes. So, this is also a difference between cytosol and S9 fraction.
Functionally, cytosol provides surface area for the cellular organelles and other cellular structures except for the cell nucleus. It also regulates the osmotic balance of the cell and assists the cells to remain viable. In contrast, S9 fraction is used to assess the metabolism of drugs and other xenobiotics. Hence, it is an important difference between cytosol and S9 fraction.
Summary – Cytosol vs S9 Fraction
Cytosol is the jelly-like matrix which houses all the structural organelles of a cell. It is the ground substance that bears structural organelles such as ribosomes, mitochondria, and chloroplast in a cell. Thus, the cytosol is a more complex and metabolically active structure in the cell. In contrast, S9 fraction is the supernatant obtained from the low-speed centrifugation of an organ homogenate. It contains both cytosol and microsomes. This is the difference between cytosol and S9 fraction.
Reference:
1. “S9” BioIVT, Available here.
2. “S9 Fraction.” Wikipedia, Wikimedia Foundation, 21 Mar. 2018, Available here.
Image Courtesy:
1. “Crowded cytosol” By TimVickers – Own work by uploader, based upon simlar illustrations in Goodsell DS (June 1991). “Inside a living cell”. Trends Biochem. Sci. 16 (6): 203–6. DOI:10.1016/0968-0004(91)90083-8. PMID 1891800 (Public Domain) via Commons Wikimedia
2. “S9 fraction” By GOKLuLe 盧樂 – Own work (CC BY-SA 3.0) via Commons Wikimedia