The discovery of noggin . The American Biology Teacher. Harland's group systematically produced protein products from the many mRNAs present in gastrula Xenopus embryos. These proteins were then tested for inducing ability. Pure noggin protein induced neural differentiation in these embryos.
Noggin protein contains a group of amino acids that bear resemblance to certain protease inhibitors.
Noggin appears to be the only protein so far discovered that is a bona fide direct neural inducer. Harland R. A cDNA has been cloned that encodes a novel polypeptide capable of inducing dorsal development in Xenopus embryos. RNA transcripts from this clone rescue normal development when injected into ventralized embryos and results in excessive head development at high doses. Noggin cDNA contains a single reading frame encoding a 26 kd protein with a hydrophobic amino-terminal sequence, suggesting that it is secreted. In the neurula, noggin is transcribed in the notochord and prechordal mesoderm.