Interacts with TGFB1I1. In the embryo, its expression is primarily restricted to the developing heart. In situ hybridization showed expression at 7.75 dpc in the paired heart-forming primordia prior to linear heart-tube formation. At 8.5 dpc, strong expression is detected in the heart, with equal expression in both heart chambers. Expression is detected in both myocardium and endocardium, and in vascular endothelium. Later in fetal development low levels of expression is detected outside the heart, including dorsal root ganglia and the spinal cord. In the adult, it is expressed at highest levels in the heart, and at lower levels in the brain, skeletal muscle and aorta.