Transcriptional activator that binds 5'-GATA-3'-containing motifs within gene promoters. Regulates cardiac-specific transcription during embryogenesis and thereby cardiogenesis. In embryos, expressed in the presumptive heart mesoderm. In adults, widely distributed but predominant in the heart. Expressed in embryos from the early gastrula stage (stage 10.5). Peak expression occurs at neurula stages (stages 11 to 17), with progressive reduction from the mid tailbud stage (stage 24) onwards. Still expressed in swimming tadpoles (stage 40) and in adults. Extended N-terminus.