actinbinding

Actinbinding is the interaction of actin with other proteins and molecules. Actin, a major cytoskeletal component, polymerizes into filaments (F-actin) from globular monomers (G-actin).

Actin-binding proteins (ABPs) regulate nucleation, elongation, capping, severing, and cross-linking of actin filaments, controlling cell shape, motility, and cytokinesis.

Common families include nucleators (formin proteins and the Arp2/3 complex), capping proteins (CapZ, tropomodulin), severing and monomer-sequestering proteins (cofilin, gelsolin, profilin), and cross-linkers (alpha-actinin, fascin, filamin).

Many ABPs use conserved actin-binding domains such as calponin homology (CH) domains or WH2 motifs to contact actin.

Regulation is achieved by calcium, phosphorylation, pH, and phosphoinositides, and binding dynamics are influenced by the nucleotide state of actin and by cooperative or competitive interactions among ABPs.

In addition to the cytoplasm, actin and ABPs function in the nucleus, influencing transcription, chromatin remodeling, and nuclear structure. Dysregulation of actinbinding processes is linked to diseases including cancer and myopathies.