Figure 3. Fluorographs of HPTLC analyses of released and radiolabeled N-glycans from purified TfR.

(A) Total N-glycan fraction of TfR released by PNGase F and radiolabeled by reduction with NaB[³H]₄. The positions of oligomannose N-linked glycan standards reduced with NaB[³H]₄ are shown on the left. The proposed structures of the principal TfR glycans are shown on the right. The top three biantennary structures (Man₃GlcNAc₂ to Man₅GlcNAc₂) are of the paucimannose series and the bottom three triantennary structures (Man₅GlcNAc₂ to Man₇GlcNAc₂) are of the oligomannose series. (B) The three major components of the radiolabeled TfR N-glycan fraction isolated by Dionex HPAEC (peaks a, b and c; lanes 1, 2 and 3, respectively). The positions of NaB[³H]₄ reduced oligomannose N-linked glycan and dextran oligomer standards are shown on the left and right, respectively. (C) The paucimannose Man₄GlcNAc₂ structure (Dionex peak a) before (lane 1) and after (lane 2) digestion with Manα1-2Man specific α-mannosidase (ASαM) and the triantennary oligomannose Man₅GlcNAc₂structure Dionex peak b before (lane 3) and after (lane 4) digestion with ASαM. The positions of NaB[³H]₄-reduced dextran oligomers are shown on right.