[11] The expression of lubricin has also been detected and the protein localized in tendon,[12] meniscus,[13] lung, liver, heart, bone,[14] ligament, muscle, and skin.

[20] The protein encoded by this gene is a approximately 345 kDa[21] specifically synthesized by chondrocytes located at the surface of articular cartilage, and also by synovial lining cells.

[16][22] Electron microscope measurements show that the lubricin molecule is a partially extended flexible rod and, in solution, occupies a smaller spatial domain than would be expected from structural predictions.

Lubricin is a close analog to vitronectin, as both of these proteins contain a somatomedin B-like (SMB) domain and a hemopexin-like chain.

[28] However, unlike vitronectin, lubricin carries a central mucin-like domain with a large number of repeating KEPAPTT motifs.

This leads to trapping of large quantities of solvent and the stabilization of a fluid-like cushioning layer, which enables bottle brush polymers to lower the friction between joints when external pressure is applied.

[38] Shear studies of lubricin adsorbed between various hydrophilic and hydrophobic surfaces have confirmed the importance of the glycoprotein in boundary lubrication and wear protection in articular joints.

[41] Lubricin, as MSF, was detected in the urine of patients undergoing bone marrow transplantation during a period of acute thrombocytopenia.

[42] Depletion of lubricin function has also been associated with camptodactyly-arthropathy-coxa vara-pericarditis syndrome (CACP), an arthritis-like autosomal recessive disorder.

[43] Extracorporeal shockwave therapy application has been shown to induce an increased lubricin expression in tendons and septa of rat hindlimbs, which might suggest a beneficial lubricating effect for joints and tissues prone to wear and tear degradation.

[46] Thus far, adding supplement lubricin has been shown to restore the lubricating ability of synovial fluid from patients with established osteoarthritis.

[48][49] Lubricin, which is naturally present in human cornea-eyelid interface, has also been shown to play a key role in reducing friction between the cornea and conjunctiva of the eye.