Amnionless Explained

Amnionless is a protein that in humans is encoded by the AMN gene.^[1]

Function

A complex of amnionless and cubilin forms the cubam receptor.

The protein encoded by this gene is a type I transmembrane protein. 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. It is known that the mouse AMN gene is expressed in the extraembryonic visceral endoderm layer during gastrulation, but it is found to be mutated in amnionless mouse. The encoded protein has sequence similarity to short gastrulation (Sog) and procollagen IIA proteins in Drosophila.^[2]

Clinical significance

Mutations of the AMN gene may cause Imerslund–Gräsbeck syndrome.

Further reading

• Kozyraki R, Gofflot F . Multiligand endocytosis and congenital defects: roles of cubilin, megalin and amnionless. . Curr. Pharm. Des. . 13 . 29 . 3038–46 . 2008 . 17979745 . 10.2174/138161207782110507 .
• Wang X, Bornslaeger EA, Haub O . A candidate gene for the amnionless gastrulation stage mouse mutation encodes a TRAF-related protein. . Dev. Biol. . 177 . 1 . 274–90 . 1996 . 8660894 . 10.1006/dbio.1996.0162 . etal. free .
• Tomihara-Newberger C, Haub O, Lee HG . The amn gene product is required in extraembryonic tissues for the generation of middle primitive streak derivatives. . Dev. Biol. . 204 . 1 . 34–54 . 1999 . 9851841 . 10.1006/dbio.1998.9034 . etal. free .
• Dunn NR, Hogan BL . How does the mouse get its trunk? . Nat. Genet. . 27 . 4 . 351–2 . 2001 . 11279507 . 10.1038/86829 . 23094701 .
• Strausberg RL, Feingold EA, Grouse LH . Generation and initial analysis of more than 15,000 full-length human and mouse cDNA sequences. . Proc. Natl. Acad. Sci. U.S.A. . 99 . 26 . 16899–903 . 2003 . 12477932 . 10.1073/pnas.242603899 . 139241 . 2002PNAS...9916899M . etal. free .
• Tanner SM, Aminoff M, Wright FA . Amnionless, essential for mouse gastrulation, is mutated in recessive hereditary megaloblastic anemia. . Nat. Genet. . 33 . 3 . 426–9 . 2003 . 12590260 . 10.1038/ng1098 . 30816649 . etal.
• Clark HF, Gurney AL, Abaya E . The secreted protein discovery initiative (SPDI), a large-scale effort to identify novel human secreted and transmembrane proteins: a bioinformatics assessment. . Genome Res. . 13 . 10 . 2265–70 . 2003 . 12975309 . 10.1101/gr.1293003 . 403697 . etal.
• Fyfe JC, Madsen M, Højrup P . The functional cobalamin (vitamin B12)-intrinsic factor receptor is a novel complex of cubilin and amnionless. . Blood . 103 . 5 . 1573–9 . 2004 . 14576052 . 10.1182/blood-2003-08-2852 . 2223309 . etal.
• Ota T, Suzuki Y, Nishikawa T . Complete sequencing and characterization of 21,243 full-length human cDNAs. . Nat. Genet. . 36 . 1 . 40–5 . 2004 . 14702039 . 10.1038/ng1285 . etal. free .
• Tsang HT, Connell JW, Brown SE . A systematic analysis of human CHMP protein interactions: additional MIT domain-containing proteins bind to multiple components of the human ESCRT III complex. . Genomics . 88 . 3 . 333–46 . 2006 . 16730941 . 10.1016/j.ygeno.2006.04.003 . etal.

Notes and References

1. Kalantry S, Manning S, Haub O, Tomihara-Newberger C, Lee HG, Fangman J, Disteche CM, Manova K, Lacy E . The amnionless gene, essential for mouse gastrulation, encodes a visceral-endoderm-specific protein with an extracellular cysteine-rich domain . Nat Genet . 27 . 4 . 412–6 . Mar 2001 . 11279523 . 10.1038/86912 . 12758039 .
2. Web site: Entrez Gene: AMN amnionless homolog (mouse).