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Description

Actin, cytoplasmic 1 (UniProt P60709, also known as beta-actin, PS1TP5-binding protein 1) is encoded by the ACTB (also known as BRWS1, PS1TP5BP1) gene (Gene ID 60) in human. Post-translational protein arginylation is mediated by Arg-transfer RNA (-tRNA) protein transferase (Ate1, arginyltransferase). beta- and gamma-actins are the major structural components of the actin cytoskeleton in nonmuscle cells. Despite their similarity, the beta-, but not the gamma-, actin is N-terminally arginylated in vivo, where the first two N-terminal amino acids are removed and replaced with an arginine (from NH2-MDDDIAAL- to NH2-RDDIAAL-). In the absence of arginylation, actin forms aggregates during cell-free polymerization. Fibroblasts derived from Ate1 knockout (KO) mice show collapsed lamella, which can be rescued by reintroducing N-terminally arginylated beta-actin into the Ate1 KO cells. Intracellular actin polymer levels are shown to drastically decrease in arginylation-deficient cells, which results from changes in actin polymerization properties.