Patterns the embryo by interrupting bone morphogenetic proteins (BMP) signaling. Binds BMP-4 and BMP-2 with high affinity. Can abolish BMP-4 activity by blocking binding to cognate cell-surface receptors. Capable of inducing dorsal development in embryos. Causes dorsal mesodermal differentiation of animal cap ectoderm when coexpressed with xWNT-8 and nuclear, sequence-specific DNA-binding protein xBRA. None of these molecules causes dorsal mesoderm formation when expressed alone. Homodimer. Expressed both maternally and zygotically. Expression starts at late blastula stages in the dorsal marginal zone and persists throughout gastrulation in the prechordal plat and the presumptive notochord, both derivatives of the Spemann organizer. At later stages expression is initiated at several new sites, including the roof plate of the neural tube and skeletogenic cells in the branchial arches. By activin. Belongs to the noggin family.