Globular actin (G-actin)

Globular actin (G-actin) is a single polypeptide chain that folds into a compact, globular structure with an ATP or ADP binding site, making it soluble and able to diffuse freely in the cell. It is the essential building block for “microfilaments” (actin filaments, or F-actin), which assemble and disassemble dynamically to support crucial cellular functions such as movement, shape maintenance, muscle contraction, and division[1][2][4][5]. G-actin can polymerize into F-actin in an ATP-dependent manner. Numerous proteins regulate transitions between G- and F-actin, including profilin, thymosin, cofilin, and gelsolin, which are critical for cytoskeletal remodeling. Dysfunction of G-actin dynamics is implicated in cancer, infection, and genetic disorders affecting muscle and cell shape. While G-actin itself is rarely the direct pharmaceutical target, many drugs and toxins act by modulating actin polymerization or sequestration, causing broad cellular effects[3][4][7].

Other names

Actin monomerMonomeric actin

Inhibition of actin polymerization (by sequestration or blocking of monomer addition, e.g. cytochalasin, latrunculin); Stabilization of F-actin filaments (indirectly affects G-actin pool, e.g. phalloidin)