Difference Between Cell Cortex and Cytoskeleton

Main Difference – Cell Cortex vs Cytoskeleton

Cell cortex and cytoskeleton are two dynamic, protein structures, involved in maintaining the shape and integrity of the cell. The cell cortex is made up of F-actin filaments, actin-binding proteins, and motor proteins. The cytoskeleton is made up of microtubules, microfilaments, intermediate filaments, and motor proteins. Cell cortex is found on the inner face of the plasma membrane while cytoskeleton is found throughout the cell periphery. The main difference between cell cortex and cytoskeleton is their function; cell cortex provides support to the plasma membrane whereas the cytoskeleton maintains the overall shape of the cell.

Key Areas Covered

1. What is Cell Cortex
      – Definition, Composition, Function
2. What is Cytoskeleton
      – Definition, Composition, Function
3. What are the Similarities Between Cell Cortex and Cytoskeleton
      – Outline of Common Features
4. What is the Difference Between Cell Cortex and Cytoskeleton
      – Comparison of Key Differences

Key Terms: Actin Cortex, Actomyosin Cortex, Cell Cortex, Cytoskeleton, F-Actin Filaments, Intermediate Filaments, Microfilaments, Microtubules, Motor Proteins

What is Cell Cortex

The cell cortex is a specialized layer of cytoplasmic proteins found in the cell periphery, which is concentrated on the inner face of the plasma membrane. The cell cortex is also known as actin cortex or actomyosin cortex. The main function of the cell cortex is to modulate the behavior of the plasma membrane and the properties of the cell surface. Since animal cells do not contain a cell wall, the cell cortex develops as an actin-rich network. This actin-rich network comprises F-actin filaments, actin-binding proteins, and myosin motors; it is attached to the cell membrane by a type of membrane-anchoring proteins called ERM proteins. The cell cortex of animal cells plays a major role in controlling the cell shape. A protein called spectrin is present in the cell cortex of some animal cells, cross-linking actin filaments.

Figure 1: F-actin filaments (red) in the cell cortex

In plant cells, cortical microtubules strengthen the cell cortex. The cell cortex is involved in forming various structures such as cell to cell adhesions, cell to substrate adhesions, and large protein aggregations, which are important in signal transduction. The F-actin proteins (red) in the cell cortex of two cells are shown in figure 1. the genetic material is stained in green.

What is Cytoskeleton

The cytoskeleton is a network made up of fibers, forming the infrastructure of both prokaryotic and eukaryotic cells. The cytoskeleton is made up of three types of protein fibers, known as microtubules, microfilaments, and intermediate filaments. Microfilaments are the thinnest fibers, and the microtubules are the thickest fibers. The microtubules (green) and the microfilaments (red) in endothelial cells are shown in figure 2. The nucleus of the cell is stained in blue.

Figure 2: Microtubules (green) and microfilaments (red) in endothelial cells

The cytoskeleton is also composed of motor proteins, which actively move fibers in the cytoskeleton. The motor proteins are powered by ATP. The three types of motor proteins in the cytoskeleton are kinesins, dyneins, and myosins. The main function of the cytoskeleton is to maintain the shape of the cell. Various organelles in the cell are held by the cytoskeleton in their relevant positions inside the cytoplasm. The cytoskeleton facilitates the formation of vacuoles. The cytoskeleton is a dynamic structure, which enables the internal and external movements of the cell. The transportation of cell signals inside the cell is also facilitated by the cytoskeleton. The cytoskeleton forms cellular protrusions such as cilia and flagella. 

Similarities Between Cell Cortex and Cytoskeleton

• Both cell cortex and cytoskeleton are protein structures involved in maintaining the shape of the cell.
• Actin filaments are motor proteins are involved in the formation of both cell cortex and the cytoskeleton.
• Since both cell cortex and cytoskeleton are made up of motor proteins, both structures are dynamic.
• Both cell cortex and cytoskeleton facilitate cell signaling.

Difference Between Cell Cortex and Cytoskeleton

Definition

Cell Cortex: The cell cortex is a specialized layer of cytoplasmic proteins found attached to the inner face of the plasma membrane.

Cytoskeleton: The cytoskeleton is a network of protein filaments and tubules found in the cytoplasm.

Function

Cell Cortex: The cell cortex modulates the behavior of the plasma membrane and the properties of the cell surface.

Cytoskeleton: The cytoskeleton provides the shape and coherence to the cell.

Composition

Cell Cortex: The cell cortex is made up of F-actin filaments, actin-binding proteins, myosin motors, and spectrin.

Cytoskeleton: The cytoskeleton is made up of microfilaments, microtubules, intermediate filaments and motor proteins.

Formation of Cellular Structures

Cell Cortex: The cell cortex is involved in forming various structures such as cell to cell adhesions, cell to substrate adhesions, and large protein aggregations, which are important in signal transduction.

Cytoskeleton: The cytoskeleton is involved in forming cellular protrusions such as cilia and flagella.

Significance in Communication

Cell Cortex: The cell cortex forms adhesions, which is important for external cell signaling.

Cytoskeleton: The cytoskeleton facilitates the transportation of cell signals inside the cytoplasm.

Conclusion

Cell cortex and cytoskeleton are two protein structures found in the cell. Both of these structures are involved in maintaining the cell shape. Actin protein fibers or microfilaments can be found in both structures. Cell cortex can be found on the inner face of the plasma membrane, maintaining the integrity of the plasma membrane. In contrast, the cytoskeleton is found throughout the cell periphery, maintaining the shape of the cell. Thus, the main difference between cell cortex and cytoskeleton is their structure and role in the cell. 

Reference:

1. “Cell cortex.” Wikipedia. Wikimedia Foundation, 26 Mar. 2017. Web. Available here. 05 July 2017.
2. Bailey, Regina. “What Is the Cytoskeleton?” ThoughtCo. N.p., n.d. Web. Available here. 05 July 2017. 

Image Courtesy:

1. “Actin-cortex” By UraniumMonkey – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “FluorescentCells” By ImageJ (Public Domain) via Commons Wikimedia