Regional differences in protein and glycoprotein synthesis and their processing in the mouse brain as revealed by the incorporation of [3H]proline, N-6-[3H]acetyl-D-glucosamine and [3H]fucose.

The incorporation rate of [3H]fucose, N-6-[3H]acetyl-D-glucosamine and [3H]proline has been compared in five regions of the mouse brain on postnatal day 6. The olfactory bulbs and the cerebellum showed a prevalence of incorporation of [3H]fucose over other brain regions. Less expressed, but still well evident regional differences were observed in [3H]proline incorporation while the incorporation of N-6-[3H]acetyl-D-glucosamine was almost equal in all brain regions. The regional differences were also apparent after considering an actual pool of free isotopes in the individual regions. Gel electrophoresis of [3H]fucose-labelled membrane fraction showed that the higher incorporation of [3H]fucose in the olfactory bulbs is partly due to higher synthesis of low molecular weight glycoproteins, especially in the molecular range of 30,000. The data showed that the protein synthesis and fucosylation, and/or a fast transport of the corresponding molecules, varies more within the brain than the incorporation of N-6-[3H]acetyl-D-glucosamine and possibly also than the "core" part of glycan molecule synthesis.