GLYCOPROTEINS IN HUMAN PAROTID-SALIVA ASSESSED BY LECTIN PROBES AFTERRESOLUTION BY SODIUM DODECYL SULFATE-POLYACRYLAMIDE GEL-ELECTROPHORESIS

Human parotid salivary glycoproteins separated by gradient sodium dode cyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and electro blotted onto nitrocellulose have been investigated using a battery of biotinylated lectin probes of characterized sugar specificity. Lectin binding, detected on blots using avidin-biotin complex (ABC) and a che miluminescence generating substrate, was recorded on photographic film and compared with the original fluorescein isothiocyanate (FITC) stai ned blots or with Coomassie Brilliant Blue R-250-stained gels run in p arallel. A number of glycoprotein bands which were undetected by prote in stains or the periodic acid Schiff reaction were revealed by lectin s. Binding from Concanavalia ensiformis, Lens culinaris, Limax flavus, Phaseolus vulgaris, Ricinus communis, Triticum vulgaris, Lotus tetrag onobulus and Ulex europaeus indicated that sialylated and fucosylated triantennary and bisected, N-linked complex sugar chains were present on many glycoproteins in addition to the major glycosylated proline-ri ch glycoprotein (Gl). Binding with lectins from Arachis hypogaea and D olichos biflorus indicated that the O-linked sugar chains were confine d to the alpha-heavy chain of Ig A. Comparison of lectin binding in sa mples from five healthy individuals revealed differences in a number o f glycoproteins in addition to the previously characterized Gl and CON 1/CON 2 polymorphisms and demonstrated that the H blood group antigen was expressed mainly on Gl in parotid saliva. This study will be used as a basis upon which to study salivary glycoproteins in diseases aff ecting parotid glands.