TMEFF1 is a type I transmembrane glycoprotein which includes 2 follistatin modules and an EGF domain in its extracellular domain， a transmembrane domain and a short cytoplasmic tail. The extracellular domain of TMEFF1 can be released as a soluble protein. TMEFF1 is primarily expressed in brain， but is downregulated in brain neoplasms. TMEFF1 selectively regulates nodal but not activin signaling through direct binding to the nodal co-receptor， Cripto. TMEFF inhibits NODAL and BMP signaling through neural patterning and also a possible tumor suppressor in brain cancers.
