AMN, also known as amnionless, is a type I transmembrane protein. A complex of amnionless and cubilin forms the cubam receptor. This protein is necessary for efficient absorption of vitamin B12. It is thought to modulate bone morphogenetic protein (BMP) receptor function by serving as an accessory or coreceptor, and thus facilitates or hinders BMP binding. Recombinant human AMN protein, fused to His-tag at N-terminus, was expressed in E.coli and purified by using conventional chromatography techniques.