HAPLN3 Background Information HAPLN3 (Hyaluronan and proteoglycan link protein 3) is a 360 amino acid protein encoded by the human gene HAPLN3. HAPLN3 belongs to the HAPLN family and contains 1 Ig-like V-type (immunoglobulin-like) domain and two Link domains. HAPLN3 mediates the binding of complexes containing hyaluronic acid. May play a pivotal role in the formation of the hyaluronan-associated matrix in the central nervous system (CNS) which facilitates neuronal conduction and general structural stabilization. HAPLN3 may also be involved in the formation of extracellular matrices contributing to perineuronal nets and facilitate the understanding of a functional role of these extracellular matrices. HAPLN3 is widely expressed with highest levels in spleen and placenta.