Acts as an activator of serum response factor (SRF)-dependent transcription possibly by inducing nuclear translocation of MKL1 or MKL2 and through a mechanism requiring Rho-actin signaling. Binds F-actin and ABLIM1, ABLIM2 AND ABLIM3. Interaction with ABLIM2 AND ABLIM3 enhances activity. Localized to the I-band of the sarcomere and to a lesser extent to the sarcomeric structure between Z-lines. Expressed specifically in heart and skeletal muscle. At 8.75 dpc, expressed in the primitive heart tube. Thereafter, expression is maintained in heart and is also detected in skeletal muscle after 10.5 dpc. The actin-binding domain 1 (ABD1) is intrinsically disordered, and binds to F-actin with higher affinity than ABD2.