Temporal Pattern of Incorporation of 3 H Precursors into Pituitary Glycoproteins and Their Subsequent Release

Abstract

Abstract

The temporal pattern of incorporation of various ³H precursors into glycoproteins by rat anterior pituitaries incubated in vitro and the release of ³H-glycoproteins was examined. [³H]Leucine incorporation was linear with respect to time and [³H]leucine-containing macromolecules appeared in the media in about 1 hr. The temporal pattern of [³H]mannose incorporation and release was similar to that observed for [³H]leucine consistent with [³H]mannose incorporation via the chitobiose core. [³H]Galactose and [³H]fucose were incorporated after apparent time delays of approximately 15 min and soon thereafter (20–25 min) appeared in the medium in ³H-glycoproteins. Thus, these precursors appear to be added as terminal residues. [³H]Glucosamine exhibited a pattern intermediate between [³H]leucine and [³H]fucose whereas [³H]GlcNAc appeared to be incorporated as a terminal residue.