Growth factor involved in bone and cartilage formation. During cartilage development regulates differentiation of chondrogenic tissue through two pathways. Firstly, positively regulates differentiation of chondrogenic tissue through its binding of high affinity with BMPR1B and of less affinity with BMPR1A, leading to induction of SMAD1-SMAD5-SMAD8 complex phosphorylation and then SMAD protein signaling transduction (By similarity). Secondly, negatively regulates chondrogenic differentiation through its interaction with NOG (By similarity). Required to prevent excessive muscle loss upon denervation. This function requires SMAD4 and is mediated by phosphorylated SMAD1/5/8 (PubMed:24076600). Binds bacterial lipopolysaccharide (LPS) and mediates LPS-induced inflammatory response, including TNF secretion by monocytes (By similarity). Homodimer; disulfide-linked (By similarity). Interacts with serine proteases, HTRA1 and HTRA3 (PubMed:15206957, PubMed:14973287). Following LPS binding, may form a complex with CXCR4, HSP90AA1 and HSPA8 (By similarity). Interacts with high affinity with NOG; inhibits chondrogenesis (By similarity). Interacts with high affinity with BMPR1B and lower affinity with BMPR1A; positively regulates chondrocyte differentiation and induces SMAD-dependent signaling. Interacts with FBN1 (via N-terminal domain) and FBN2 (By similarity). Induced over 300-fold in tibialis anterior muscles 3 days following denervation. High expression is maintained at least until 10 days after denervation. Defects in Gdf5 are the cause of brachypodism (bp) which alters the length and numbers of bones in the limbs but spares the axial skeleton. Belongs to the TGF-beta family.