Xenbase Image ID: 159339

Figure 2. The Chordin/Tolloid/BMP morphogenetic pathway. This pathway patterns the D-V axis of the Xenopus gastrula. A self-regulating gradient of BMP activity results from direct protein–protein interactions between Chordin and other partners, indicated by black lines. Blue arrows indicate transcriptional regulation by BMP signaling, which is maximal in the ventral and lowest in the dorsal center. Red arrows indicate protein flux of Chordin-BMP complexes in a narrow signaling highway located in the extracellular matrix that separates the ectoderm from the endomesoderm. Tolloid constitutes the rate-limiting step, serving as a Chordin proteinase. Note that BMPs have a dual regulatory activity on Tolloid metalloproteinase: they stimulate Tolloid (Xlr) transcription, and they inhibit Tolloid enzymatic activity non-competitively by binding to the CUB domains. Sizzled is a competitive inhibitor of Tolloid that is bound by the active site but not cleaved. Image published in: De Robertis EM et al. (2017) Copyright © 2017. Image reproduced with permission of the Publisher, John Wiley & Sons. Larger Image Printer Friendly View

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