A key element of this proposal is to develop an in situ system for an in depth analysis of the stimulus-secretion-synthesis cycle of a mucin from the submandibular glands of mice. The information gathered will be applied toward understanding mechanisms for control of synthesis and processing of salivary mucin. The stimulus-secretion-synthesis system will be standardized so that what is learned may serve as reference for future studies of salivary gland dysfunction such as xerostomia, sialorrhea and chronic enlargement. The amounts, rates of synthesis and rates of degradation of the mucin will be quantitated at each phase of the cycle by utilizing radioimmunoassay and immunoprecipitation of mucin polysomes. In addition, a protocol is described that will provide accurate timing of the glycosylation events. Possible control interactions between translation and oligosaccharide assembly will be investigated with the help of tunicamycin. The effects of various doses of different secretagogues on the stimulus-secretion-synthesis cycle will be compared. A procedure which allows for an assessment of the mucin content of an individual's glands prior to secretory stimulation will be used. Flow rates, mucin and protein contents of saliva, as well as mucin nascent polypeptides and mucin polysome contents of glands will be obtained. Finally, the possibility that mucin oligosaccharides undergo a processing step at secretion will be investigated. A protocol will be used that provides for carbohydrate analyses of the mucin from the same individual before and after secretion.
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