Transcriptional cofactor that restricts GATA6 function by inhibiting DNA-binding, resulting in repression of GATA6 transcriptional activation of downstream target genes. Represses GATA6-mediated trans activation of lung- and cardiac tissue-specific promoters. Inhibits DNA-binding by GATA4 and GATA1 to the cTNC promoter. Plays a critical role in the development of cardiac hypertrophy via activation of calcineurin/nuclear factor of activated T-cells signaling pathway. Interacts with beta-dystroglycan (By similarity). Interacts with GATA1, GATA4 and GATA6. May shuttle between the cytoplasm and the nucleus. Expressed in distal airway epithelium of the lung, vascular smooth muscle, and myocardium. At 9.5 dpc expressed in the myocardium and forming anterior foregut epithelium. By 12.5 dpc, expression is observed in the airways of the developing lung as well as in the myocardium. At 14.5 dpc, when proximal-distal differentiation in the lung is proceeding rapidly, expression is observed at high levels in the distal but not proximal airways of the developing lung. By 16.5 dpc, expression decreases in airway epithelium in the lung and expression is also observed in the vascular smooth muscle of pulmonary arteries (at protein level). The LIM zinc-binding domains and the Cys-rich region mediate interaction with GATA6. Mice display a marked increase in cardiac hypertrophy.