Transcription coactivator that associates with the serum response factor (SRF) transcription factor to control expression of genes regulating the cytoskeleton during development, morphogenesis and cell migration. The SRF-MRTFA complex activity responds to Rho GTPase-induced changes in cellular globular actin (G-actin) concentration, thereby coupling cytoskeletal gene expression to cytoskeletal dynamics. MRTFA binds G-actin via its RPEL repeats, regulating activity of the MRTFA-SRF complex. Activity is also regulated by filamentous actin (F-actin) in the nucleus.
A chromosomal aberration involving MRTFA may be a cause of acute megakaryoblastic leukemia. Translocation t(1;22)(p13;q13) with RBM15 (PubMed:11431691, PubMed:11344311). Although both reciprocal fusion transcripts are detected in acute megakaryoblastic leukemia (AMKL, FAB-M7), the RBM15-MRTFA chimeric protein has all the putative functional domains encoded by each gene and is the candidate oncogene (PubMed:11431691, PubMed:11344311).