BMP and activin membrane-bound inhibitor homolog, also known as BAMBI, is a protein which in humans is encoded by the BAMBI gene.
This gene encodes a transmembrane glycoprotein related to the type I receptors of the transforming growth factor-beta (TGF beta) family. The encoded protein is a pseudoreceptor that lacks an intracellular serine/threonine kinase domain required for signaling. Similar proteins in frog, mouse and zebrafish function as negative regulators of TGF-beta. Therefore, this has led to the suggestion that the encoded protein may function to limit the signaling range of the TGF-beta family during early embryogenesis.