Secretory Proteins and Glycoconjugates Synthesized by Human Tracheal Gland Cells in Culture

To study the proteins and glycoconjugates synthesized by serous cells from human tracheal glands (HTG), isolated HTG cells were cultured in the presence of radiolabeled precursors 14C-proline, Na235SO4, and 3H-fueose. The secretory 14C/35S/3H-radiolabeled proteins and glycoproteins, de novo synthesized by HTG cells, were analyzed by gel filtration chromatography. We observed the incorporation of 14C-proline into antileukoprotease and an unknown 30 kD protein, and the incorporation of 35SO4−− and 3H-fucose into high molecular weight glycoconjugates and sulfoconjugates (Mr > 1,000,000) and into components with apparent Mr of approximately 250 and 100 kD. After specific chemical and enzymatic treatment, the 35S- and 3H-glycoconjugates were shown to be -O-linked mucin-like glycoproteins and proteoglycans. These results show that cultured HTG cells synthesize some of the macromolecules identified in bronchial secretions.