GLYCOSYLATION OF SECRETORY PROTEINS IN SALIVARY-GLANDS AND SALIVA STUDIED BY LECTIN-PROBES

Lectin-probes were used histochemically to study glycosylation pattern s in prepackaged secretory material in cat and rat submandibular gland s and to assess the secretory changes induced by nerve stimulations. T he same probes were also used for correlative biochemical assessments of the constituents in glandular extracts and in saliva from the same experiments, after electrophoretic separations and immobilization on n itrocellulose membranes. These studies provided a broader understandin g than the use of either procedure alone. Lectin binding patterns in s aliva were more complex than anticipated from the histochemistry and t his probably relates to the presence of different constituents in secr etory granules and a greater availability of binding sites biochemical ly. In cats, parasympathetic stimulation caused depletion of lectin st aining in acini and to some extent in demilunes, whereas sympathetic s timulation caused depletion of lectin binding in striated ducts and re duction in demilunar size. Biochemically after SDS-PAGE of saliva simi lar secretory effects were observed but each nerve also evoked some se cretion from the cells not showing histochemical change. In rats, symp athetic stimulation caused depletion of lectin positive granules from both acini and granular tubules. After SDS-PAGE of the saliva one zone of lectin binding 94 - 150 kD (Mr) was identified as acinar mucin. Gr anular tubule proteins consisting mainly of kallikreins occurred in a zone 25 - 35 kD (Mr) and lectin bindings suggested that different kall ikreins may be differently glycosylated. This unexpected possibility w as confirmed on slot-blot preparations of separated kallikreins, which also revealed the novel finding that some kallikreins are O-as well a s N-glycosylated.