Bmp5 is a secreted ligand of the TGF-beta (transforming growth factor-beta) superfamily of proteins. Ligands of this family bind various TGF-beta receptors leading to recruitment and activation of SMAD family transcription factors that regulate gene expression. The encoded preproprotein is proteolytically processed to generate each subunit of the disulfide-linked homodimer, which plays a role in bone and cartilage development. Mice with null mutations in this gene exhibit a short ear phenotype, which is characterized by reduced size of the external ear, altered size and shape of the sternum, and other skeletal and soft-tissue abnormalities.