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 (By similarity). Localized to the I-band of the sarcomere and to a lesser extent to the sarcomeric structure between Z-lines. Specifically expressed in heart and skeletal muscles. Expression increase gradually from 33 dpc (days post-coitum) to postnatal muscles, and peaks at 28 days postnatal. The actin-binding domain 1 (ABD1) is intrinsically disordered, and binds to F-actin with higher affinity than ABD2.