What factors influence actin filament length and treadmilling?
Several factors influence actin filament length and treadmilling ATP binding on G-actin and free ATP-G-actin concentration ATP-binding on actin subunits modulates the dynamics of filament assembly, with ATP-binding generally favoring intersubunit interactions and thereby filament assembly.
How are actin, myosin and filament sliding related?
In addition to binding actin, the myosinheads bind and hydrolyze ATP, which provides the energy to drive filament sliding. This translationof chemical energy to movement is mediated by changes in the shape of myosin resulting from ATP binding.
How is the Assembly of actin filament modulated?
Actin filament assembly can be modulated by events such as controlled nucleotide hydrolysis (e.g. ATP on actin) and reversible modifications (e.g. phosphorylation) on components that control actin assembly. The (-) and (+) ends have a different criticial concentration (Cc) for actin filament growth.
What is the role of hydrolysis in filament treadmilling?
ATP hydrolysis on actin is the key reaction that allows filament treadmilling. It regulates barbed-end dynamics and length fluctuations at steady state and specifies the functional interaction of actin with essential regulatory proteins such as profilin and ADF/cofilin.
How does phalloidin inhibit disassembly of actin filament?
Phalloidins inhibit actin filament disassembly by locking adjacent actin subunits together, while cytochalasins bind to the barbed end of actin filaments to prevent actin filament assembly and disassembly at that end.
How do actin monomers dissociate from the filament?
Actin monomers intrinsically dissociate from the barbed end at a faster rate than they do from the pointed end . This is counteracted by the binding of capping proteins or formins to the barbed end, creating a more stable filament.