Fig. 1. The T box proteins Xbra, VegT and Eomesodermin are expressed in similar patterns but induce the expression of different genes. (A) The structures of Xbra, VegT and Eomesodermin. Note that Eomesodermin has a larger N-terminal domain than Xbra or VegT. (B) Expression of Xbra at the early gastrula stage analysed by whole-mount in situ hybridisation. (C) Expression of VegT at the early gastrula stage. (D) Expression of Eomesodermin at the early gastrula stage. (E) Different inducing properties of Xbra, VegT and Eomesodermin. Note that all three T box proteins induce expression of Wnt11 and Bix4, that VegT and Eomesodermin induce higher levels of Pintallavis and Sox17 than does Xbra, and that Xbra cannot activate Goosecoid, chordin, Xwnt8 or Mix.1. The expression domains of the marker genes are as follows: Xwnt11, pan-mesodermal (Tada and Smith, 2000); Bix4, pan-mesendodermal (Casey et al., 1999; Tada et al., 1998); Pintallavis, dorsal mesoderm (Ruiz i Altaba and Jessell, 1992); Sox17, endodermal (Hudson et al., 1997); Goosecoid: dorsal mesendoderm (Cho et al., 1991); chordin: dorsal mesoderm (Sasai et al., 1994); Xwnt8, ventral and lateral mesoderm (Christian et al., 1991; Smith and Harland, 1991); and Mix.1, pan-mesendodermal (Rosa, 1989).