Negatively regulates bone density. Antagonizes the ability of certain osteogenic BMPs to induce osteoprogenitor differentitation and ossification. Homodimer; disulfide-linked. Adult mice lacking BMP3 have increased bone mass (PubMed:11138004). Targeted loss of BMP3 results also in increased differentiation of early osteoblasts precursors into mature osteoblasts and further supports a role of BMP3 in regulating adult bone mass (PubMed:22074949). Belongs to the TGF-beta family.