BMPR1A

The BMPR1A gene provides instructions for making a protein called bone morphogenetic protein receptor 1A. This receptor protein has a specific site into which certain other proteins, called ligands, fit like keys into locks. Specifically, the BMPR1A protein attaches (binds) to ligands in the transforming growth factor beta (TGF-β) pathway. This signaling pathway allows the environment outside the cell to affect how the cell produces other proteins. The BMPR1A receptor protein and its ligands are involved in transmitting chemical signals from the cell membrane to the nucleus.

When the BMPR1A protein is bound to a ligand, it turns on (activates) a group of related proteins (a protein complex) called SMAD proteins. The activated SMAD protein complex is then transported into the cell's nucleus, where it regulates cell growth and division (proliferation) and the activity of particular genes.

juvenile polyposis syndrome - caused by mutations in the BMPR1A gene

More than 60 mutations in the BMPR1A gene have been found to cause juvenile polyposis syndrome. Most BMPR1A gene mutations result in the production of an abnormally short, nonfunctional protein. As a result, the BMPR1A protein cannot bind to ligands in the TGF-β pathway. This disruption in binding interferes with the activation of the SMAD protein complex. This inactive complex is not transported to the nucleus, where it is needed to regulate cell growth and the activity of certain genes. Unregulated cell growth can lead to polyp formation in people with juvenile polyposis syndrome.