This domain family is found in eukaryotes, and is approximately 100 amino acids in length. The family is found in association with pfam02191. There are two conserved sequence motifs: SAQ and VQN. Noelin-1 is a glycoprotein which is secreted mainly by postmitotic neurogenic tissues in the developing central and peripheral nervous systems, first appearing after neural tube closure. It is likely that it forms large multimeric complexes.It has a divergent function in neurogenesis. In animal caps neuralized by expression of noggin, co-expression of Noelin-1 causes expression of neuronal differentiation markers several stages before neurogenesis normally occurs in this tissue. Finally, only secreted forms of the protein can activate sensory marker expression, while all forms of the protein can induce early neurogenesis.