OCULAR MUCINS - PURIFICATION, METABOLISM AND FUNCTIONS

Mucins are present at the ocular surface in both secreted and membrane -bound forms. Mucins are produced in part by the conjunctival goblet c ells, and are complemented by non-goblet secretions. This review focus es on secreted ocular mucins. They are present in the tear film, proba bly both in gel and soluble form, and play a role in lubrication and o cular defence. It is apparent that mucins are highly adapted to their functions. State of the art techniques for mucin purification and anal ysis are presented. Density gradient centrifugation, gel filtration, i on-exchange chromatography and agarose gel electrophoresis are discuss ed, together with methods of oligosaccharide analysis. Reagents for th e detection of mucin are considered in conjunction with these methods, which we have employed in the analysis of human and canine ocular muc ins. The general structure of mucins is reviewed. The biosynthesis and glycosylation of ocular mucins are not yet fully understood, and are discussed in relation to currently established concepts. The impact of disease on the nature and secretion of mucins is considered, as well as the physiological and pathological significance of mucus degradatio n.