Actin
Category: Proteins · Last updated
Actin is a 42 kDa globular protein and the most abundant protein in most eukaryotic cells. It exists in dynamic equilibrium between monomeric G-actin and polymerized F-actin (filamentous actin), which together form the actin cytoskeleton — the structural and contractile scaffold underlying cell shape, migration, division, and muscle contraction.
G-actin vs F-actin
The G-actin / F-actin balance is shifted by:
- ATP-G-actin → F-actin polymerization (favors filament growth)
- F-actin → ADP-G-actin depolymerization (favors filament breakdown)
- Sequestering proteins that bind G-actin and prevent polymerization — including Thymosin Beta-4, the dominant such protein in eukaryotic cells
Relevance to research peptides
- TB-500 · synthetic 7-residue fragment of Thymosin Beta-4 (Ac-LKKTETQ, residues 17–23) retaining the actin-binding activity of the parent protein