PDF《Scaling of the BMP Morphogen》

5 1.5 Screen Results: Parameter Ratios Over 26,000 parameter sets were scanned. Of these, 4.3% (1127) established a biologically valid gradient. Only

39 also scaled properly, and

21 of those

39 were robust. Thus, only

21 (0.08% of the networks) were found to be consistent. The consistent sets were con?ned to a small subspace within the nine dimensional parameter space. As is detailed in the main text, all consistent sets had high ratios of DComp/Dlig and of λLig Chd/λChd, with λLig Chd = max(λBmp Chd , λAdmp Chd ). Note that degradation rate of the free Chordin competes with degradation rates of Chordin-Bmp and Chordin-Admp. Those two properties are essential for the shuttling mechanism (see analysis in sec- tions 3-4). Moreover, most consistent sets had a low ratio kAdmp/kBmp which is required for scaling (see analysis in section 3). Sets neighboring this sub- space were often partially successful, showing, for example, a valid gradient but failing to scale. 1.6 Shuttling Coe?cient To characterize the mecha........