Cooperation and regulatory loops of multiple nodals are essential for mesendoderm patterning in early embryos. Plays a role in mesoderm formation and may be required for neural development. Homodimer; disulfide-linked. During blastula stages, expressed in the endoderm at a higher level dorsally than ventrally. Expressed in the deep cells of the Spemann organizer at the gastrula stage. Expressed in the notochord (a derivative of the organizer) and neural tube during the neural stages. Expressed zygotically. First expressed at the midblastula transition (MBT). By dorsal-mesoderm inducing signals including vegt and other nodal-related proteins. By sox17. Belongs to the TGF-beta family.