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. May play a role in regulating the mature length of the middle and short rows of stereocilia (By similarity). Interacts with G-actin; ADP-actin form and capping protein (CP). May also be able to interact with TWF1 and phosphoinositides, PI(4,5)P2. When bound to PI(4,5)P2, it is down-regulated. Interacts with MYO7A (By similarity). Perinuclear and G-actin-rich cortical actin structure sublocalization. Phosphorylated on both serine and threonine residues. Belongs to the actin-binding proteins ADF family. Twinfilin subfamily. Molecular embrace - Issue 73 of August 2006