Figure 2
From: Digit patterning during limb development as a result of the BMP-receptor interaction
The model.
(A) The network represents the regulatory interactions that were considered in the model. Thus BMP binds the receptor reversibly to form BMP–receptor complexes. BMP-receptor complexes induce the production of receptors and enhances FGF activity. FGF induces BMP expression. (B) The effective regulatory interactions as captured by Eq (9)–(11). Thus BMP, B, has a positive impact on receptors, R and on FGF, F, (both via BMP-receptor complexes that are not included here). Receptors are auto-activating (when bound by BMP), while BMP are auto-inhibitory (as they enhance their own decay by receptor binding). FGF and BMP are mutually enhancing each other. For more details see text. (C) The computational domain based on the shape of an E11.5 limb bud. The values for the different lengths are summarized in Table S1. Ri are the radial axes of the elliptical limb bud. H0 and W0 are the height and width of the stalk. H1 represents the height of the domain in the stalk where the BMP expression is enhanced. The dashed line indicates the AER where AER-FGFs are expressed. For details see text.
