This proteoglycan is a major component of extracellular matrix of cartilagenous tissues. A major function of this protein is to resist compression in cartilage. It binds avidly to hyaluronic acid via an N-terminal globular region. May play a regulatory role in the matrix assembly of the cartilage. Two globular domains, G1 and G2, comprise the N-terminus of the proteoglycan, while another globular region, G3, makes up the C-terminus. G1 contains Link domains and thus consists of three disulfide-bonded loop structures designated as the A, B, B' motifs. G2 is similar to G1. The keratan sulfate (KS) and the chondroitin sulfate (CS) attachment domains lie between G2 and G3. Contains mostly chondroitin sulfate, but also keratan sulfate chains, N-linked and O-linked oligosaccharides. Defects in ACAN are the cause of nanomelia, a lethal connective tissue disorder affecting cartilage development (chondrodystrophy) characterized by shortened and malformed limbs. Aggrecan is truncated at its C-terminus in the CS-2 binding domain and is not anymore secreted from the chondrocytes. Belongs to the aggrecan/versican proteoglycan family.