Noggin inhibits TGF-beta signal transduction by binding to TGF-beta family ligands and preventing them from binding to their corresponding receptors. Noggin plays a key role in neural induction by inhibiting BMP4, along with other TGF-beta signaling inhibitors such as chordin and follistatin. Mouse knockout experiments have demonstrated that noggin also plays a crucial role in bone development, joint formation, and neural tube fusion.
The secreted polypeptide noggin, encoded by the NOG gene, binds and inactivates members of the transforming TGF-beta superfamily signaling proteins, such as BMP4. By diffusing through extracellular matrices more efficiently than members of the TGF-beta superfamily, noggin may have a principal role in creating morphogenic gradients.