Aggrecan is a large proteoglycan found primarily in cartilage, which is the flexible tissue that cushions joints. It plays a crucial role in providing cartilage with its unique ability to withstand compressive forces, helping to maintain the structure and function of joints. Aggrecan is composed of a core protein with numerous glycosaminoglycan (GAG) chains attached, which attract water and create a gel-like matrix. This matrix allows cartilage to absorb shock and distribute loads during movement, making aggrecan essential for joint health and mobility.