Confocal immunofluorescent analysis of HeLa cells using Lamin A/C (4C11) Mouse mAb (Alexa Fluor® 488 Conjugate) #8617 (green). Actin filaments were labeled with Alexa Fluor® 647 Phalloidin (blue pseudocolor).
Actin, a ubiquitous eukaryotic protein, is the major component of the cytoskeleton. At least six isoforms are known in mammals. Nonmuscle β- and γ-actin, also known as cytoplasmic actin, are predominantly expressed in nonmuscle cells, controlling cell structure and motility (1). Actin exists mainly as a fibrous polymer, F-actin. In response to cytoskeletal reorganizing signals during processes such as cytokinesis, endocytosis, or stress, cofilin promotes fragmentation and depolymerization of F-actin, resulting in an increase in the monomeric globular form, G-actin (2). Phalloidin is a natually occuring toxic bicyclic peptide found in the deathcap toadstool, Amanita phalloides, that rapidly binds to F-actin with strong affinity (3).