Xenbase Image ID: 133471

Figure 7. Enzymatic regulation of Xenopus D–V patterning. This diagram depicts the extracellular network of biochemical protein–protein interactions that establishes the embryonic D–V axis through protein–protein interactions (black arrows), BMP-dependent transcription (blue arrows), and the flux of Chordin/BMP complexes from more dorsal regions to the ventral side, where it is bound by CV2 (red arrows). Tolloid and CV2 act as sinks for Chordin in the ventral side, where BMPs made in more dorsal regions can be released by Tolloid to reach peak signaling levels. The system is self-regulating because transcription of dorsal genes is repressed by BMP signals, while ventral genes are under the opposite transcriptional regulation (Reversade and De Robertis 2005; Lee et al. 2006; Ambrosio et al. 2008; Ben-Zvi et al. 2008). The two new reactions reported in this study are the inhibitory black arrows from BMP4/7 to Tolloid in the ventral side (enzyme activity inhibition) and from Tolloid to BMP4/7 (inhibition through binding and sequestration of the growth factor). Other important regulators of D–V patterning, such as Noggin and Follistatin (Khokha et al. 2005), are not included in this simplified model. Image published in: Lee HX et al. (2009) Copyright © 2009. Image reproduced on with permission of the Publisher, Cold Spring Harbor Laboratory Press. This is an Open Access article. Larger Image Printer Friendly View

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