Glycoproteins from the hamster respiratory tract and their response to vitamin A

1. 1. Lung and tracheal glycopeptides were isolated from hamsters after tissues were incubated with labeled sugar precursors. The uptake of labeled glucosamine and fucose into the glycopeptides isolated from lung was not affected by either deficiency or excess of vitamin A. On the other hand, in vitamin A deficiency, trachea showed a markedly lower incorporation of [³H]fucose into one glycopeptide fraction eluted by 0.2 M LiCl from DEAE-Sephadex. 2. 2. This fraction did not respond to excess retinyl palmitate feeding, but its labeled fucose uptake increased by more than 100% when the animals were fed excess retinoic acid for 6 weeks. 3. 3. Recovery to normal levels of the depressed [³H]fucose uptake into the 0.2 M fraction occured within 1-2 days after feeding vitamin A to deficient hamsters. 4. 4. Further purification of this 0.2 M fraction on Sephadex G-75 yielded several [¹⁴C]glucosamine-containing components, only one of which component [³H]fucose. Uptake of both [¹⁴C]glucosamine and [³H]fucose into this component was greatly reduced in vitamin A deficiency. Further purification of this component on Sephadex G-75 and on Sephadex G-50, yielded a single, [³H]fucose-containing peak that contained mannose, galactose, hexosamines, fucose, and sialic acid in the ratio 1 : 1.6 : 2.7 : 0.1 : 0.1. The homogeneity of this peak was confirmed by polyacrylamide gel electrophoresis.