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. Interacts with G-actin; ADP-actin form and capping protein (CP) (PubMed:12807912, PubMed:15282541, PubMed:16511569). May also be able to interact with TWF2 and phosphoinositides, PI(4,5)P2 (PubMed:12807912). When bound to PI(4,5)P2, it is down-regulated (PubMed:12807912). Interacts with ACTG1 (By similarity). Diffuse cytoplasmic localization with perinuclear and G-actin-rich cortical actin structures sublocalization. Also found at membrane ruffles and cell-cell contacts. Widely expressed with highest levels in brain, liver and kidney. Also expressed in heart, lung and testis. Not detected in spleen or skeletal muscle. Expression was widespread throughout the embryonic stages analyzed; 10.5 dpc, 12.5 dpc, 14.5 dpc and 18.5 dpc. At 14.5 dpc, strongest expression was observed in the developing central and peripheral nervous system (CNS and PNS, respectively) and in the olfactory sensory epithelium. In the CNS, the proliferating neuronal precursors in the ventricular zone expressed it more than the postmitotic neurons. At 18.5 dpc, highest expression levels were detected in the mechanosensory hair cells of the inner ear and in the differentiated keratinocytes of the skin. Phosphorylated on serine and threonine residues. Belongs to the actin-binding proteins ADF family. Twinfilin subfamily. Molecular embrace - Issue 73 of August 2006