Actin-binding protein involved in motile and morphological processes. Inhibits actin polymerization, likely by sequestering G-actin. By capping the barbed ends of filaments, it also regulates motility. Seems to play an important role in clathrin-mediated endocytosis and distribution of endocytic organelles (By similarity). Interacts with G-actin; ADP-actin form and capping protein (CP). May also be able to interact with TWF2 and phosphoinositides, PI(4,5)P2. When bound to PI(4,5)P2, it is down-regulated. Interacts with ACTG1. Diffuse cytoplasmic localization with perinuclear and G-actin-rich cortical actin structures sublocalization. Also found at membrane ruffles and cell-cell contacts (By similarity). Phosphorylated on serine and threonine residues. Belongs to the actin-binding proteins ADF family. Twinfilin subfamily. Molecular embrace - Issue 73 of August 2006