Actin Treadmilling: Difference in Critical Concentrations Explained

  • Thread starter Imperfectus
  • Start date
In summary, there is a difference in the critical concentrations at the two ends of the actin molecule due to the reactions taking place. However, if a T form is added or a D form is removed at any end, the resulting molecule will be the same. This is because the reaction is essentially identical at both ends. The polar structure of actin monomers and polymers also contributes to the difference in polymerization and depolymerization kinetics at each end. The presence of a GTPase or ATPase also affects this process. Additionally, actin (de)polymerization is highly regulated in cells, with various proteins such as cofilin and formin playing a role. Further research on the regulation of actin chains
  • #1
Imperfectus
1
0
The critical concentrations at the two ends are different because the reactions taking place are different (addition of a T form and removal of a D form G actin)
but, if you add a T form at any end, the resulting molecule will be the same, and if you remove a D form from any end, the resulting molecule will be the same. so, this reaction is essentially identical at both ends, right? can someone please explain why there is a difference in the critical concentrations here?
 
Biology news on Phys.org
  • #2
Going from memory here. Actin monomers and polymers are polar structures, meaning their structure shows unique characteristics at each 'end.' This polarity gives rise to the difference in polymerization and depolymerization kinetics at either end. Also, don't forget that actin monomers have a GTPase (or ATPase, whichever one actin binds) which effects the polymerization and depolymerization process.

In addition, don't forget that actin (de)polymerization is a highly regulated process. Cells don't just build up and tear down actin all willy nilly. For further reading you should read up the regulation of actin chains due to things like cofilin, formin, capping proteins etc. There are many of them out there. A month ago I could've likely written several pages up for you to read but alas, I have forgotten many of the details now.
 
  • Like
Likes Ygggdrasil

1. What is actin treadmilling?

Actin treadmilling is the process by which actin filaments, a major component of the cell's cytoskeleton, continuously grow and shrink at their ends. This allows for the dynamic movement and shape changes of cells, such as cell division and migration.

2. How is treadmilling different from other forms of actin polymerization?

The main difference between treadmilling and other forms of actin polymerization, such as nucleation and elongation, is that it occurs at both ends of the filament simultaneously. Treadmilling is also a steady-state process, meaning that the rate of growth at one end is balanced by the rate of shrinkage at the other end.

3. What is the critical concentration of actin and how does it affect treadmilling?

The critical concentration is the concentration of free actin monomers at which the rate of polymerization equals the rate of depolymerization. At concentrations below the critical concentration, actin filaments will disassemble, while at concentrations above the critical concentration, they will grow. This critical concentration is important for maintaining the balance of actin treadmilling.

4. How is the critical concentration different for the two ends of the actin filament?

The critical concentration is typically higher at the barbed end (the end where polymerization occurs) compared to the pointed end (the end where depolymerization occurs). This is because the barbed end has a higher affinity for actin monomers, making it easier for filaments to grow at this end.

5. What factors can affect the critical concentration and therefore, actin treadmilling?

The critical concentration can be influenced by various factors, such as the presence of actin-binding proteins that can either promote or inhibit polymerization, changes in pH or ionic strength, and the concentration of ATP, which is used as an energy source for actin polymerization. Alterations in these factors can disrupt the balance of actin treadmilling and affect cell functions.

Similar threads

Replies
131
Views
4K
  • Chemistry
Replies
9
Views
815
Replies
3
Views
3K
  • Chemistry
Replies
1
Views
632
  • Biology and Medical
Replies
4
Views
2K
Replies
27
Views
2K
  • Set Theory, Logic, Probability, Statistics
Replies
4
Views
979
Replies
4
Views
1K
Back
Top