Incorporation of inorganic [35S]-sulphate into glycoproteins of rat buccal and palatal minor salivary glands in vivo and in vitro.

The incorporation of sodium [35S]-sulphate into the buccal and palatal minor glands of the albino rat was studied in vivo and in vitro. The biosynthesis of 35S-labelled macromolecules possessing the characteristics of sulphated glycoproteins was evident in both. Uptake of [35S]-sulphate into the palatal tissue in vivo was more rapid (approx. 10-fold at 2 h) and produced compounds of higher specific activity by comparison with buccal extracts. Following in-vitro culture in the presence of [35S]-sulphate, the 35S-labelled glycoproteins secreted into the medium contained a greater proportion of lower molecular-weight products and were of higher specific activity (in the range 10-20-fold greater) than those in the tissue fraction. No sulphated glycosaminoglycans were apparent in any of the products isolated.