Actin-binding Rho-activating protein (ABRA)

Actin-binding Rho-activating protein (ABRA), also known as Striated muscle activator of Rho signaling (STARS), is a conserved actin-binding protein highly enriched in cardiac, skeletal, and smooth muscle. ABRA localizes to the sarcomere, binding actin at the Z-disc and M-line, and regulates actin polymerization through interactions with actin-binding LIM (ABLIM) proteins. By promoting the conversion of G-actin to F-actin, ABRA removes G-actin-mediated inhibition of transcriptional co-activators (such as MRTFA), which allows these modulators to activate serum response factor (SRF)-dependent gene expression, thereby influencing muscle cell proliferation, differentiation, and response to mechanical and stress stimuli[1][3][4]. ABRA is downregulated in pathological states such as dilated cardiomyopathy and upregulated in muscle hypertrophy, playing a critical role in sarcomere integrity and as a modulator in muscle physiology and disease. Although it participates in key muscle signaling pathways, it is not currently considered a primary therapeutic target or receptor and no drugs are known to directly target ABRA[4][3][1].

Other names

Striated muscle activator of Rho signaling (STARS)Myocyte stress-1 (MS1)Actin binding Rho activating protein