Affects the rate of fibrils formation. May have a primary role in collagen fibrillogenesis. Binds to type I and type II collagen. Highest levels observed in knee epiphysis, in calvarial and diaphyseal bone, in nasal and costal cartilage, in the eye, and in bladder. In mature knee joint it is mostly present in the proliferating zone of growth plate. It is also observed in ligaments, especially at insertion sites, in the junction between meniscus and joint capsule, in the perimysium of skeletal muscle and in the periosteum. Highest levels between 5 days and 1 month of age. Thereafter, the expression of declined to a level of approx. 35% of maximum, and remained constant throughout the rest of the observation period. Binds keratan sulfate chains. Sulfated on tyrosine residue(s). Belongs to the small leucine-rich proteoglycan (SLRP) family. SLRP class II subfamily.