This domain is found both alone and at the C-terminus of actin-binding Rho-activating protein (ABRA). It binds to actin, and in muscle regulates the actin cytoskeleton and cell motility [1-2]. It has a winged helix-like fold consisting of three alpha-helices and four antiparallel beta strands. Unlike typical winged helix proteins it does not bind to DNA, but contains a hydrophobic groove which may be responsible for interaction with other proteins [3].

1: STARS, a striated muscle activator of Rho signaling and serum response factor-dependent transcription. Arai A, Spencer JA, Olson EN; J Biol Chem. 2002;277:24453-24459. PMID:11983702

2: Costars, a Dictyostelium protein similar to the C-terminal domain of STARS, regulates the actin cytoskeleton and motility. Pang TL, Chen FC, Weng YL, Liao HC, Yi YH, Ho CL, Lin CH, Chen MY; J Cell Sci. 2010;123:3745-3755. PMID:20940261

3: Solution structure of the human HSPC280 protein. Lin J, Zhou T, Wang J; Protein Sci. 2011;20:216-223. PMID:21082705