TMEFF1, also known as tomoregulin-1, is a type I transmembrane glycoprotein. This protein contains two 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 predominantly 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. Recombinant human TMEFF1 protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.