Comparison in vitro of the incorporation of D-[2-3H(N)]-mannose and D-[1-14C]-glucosamine into glycoproteins of dispersed rat submandibular salivary gland cells.

The incorporation of two different radiolabelled sugars, D-[14C]-glucosamine and D-[2-3H(N)]-mannose, into cellular and secretory glycoproteins was compared using dispersed rat submandibular cells. Most of the de-novo biosynthesis appeared to be directed toward the synthesis of secretory material as the molecular profile of the 3H-labelled material released following sympathomimetic stimulation and the percentage of total 3H-labelled acid--precipitable material secreted following cholinergic- or adrenergic-receptor stimulation coincided with the data obtained from similar studies using [14C]-glucosamine. The [3H]-mannose label was found in the neutral sugars mannose, galactose, glucose and fucose, with trace amounts of radiolabel in the amino sugars, whereas the [14C]-glucosamine label was present in three different amino sugars; glucosamine, galactosamine and sialic acid.