Differential and cell-type specific microheterogeneity of high mannose-type Asn-linked oligosaccharides of human transferrin receptor

The structural analysis of high mannose-type Asn-linked (N-linked) oligosac charides of the human transferrin receptor (hTR) from D-[2-H-3]mannose meta bolic-radiolabeled human cells - A431, K562, BeWo, and HL60 - was investiga ted. The radiolabeled hTR glycopeptides were prepared and fractionated by a lectin chromatography of Concanavalin A-Sepharose. The composition analysi s of hTR glycopeptides revealed that Con A-I contains both mannose and fuco se, whereas Con A-III has mannose exclusively. The Con A-III glycopeptides were treated with Endo H. The released oligosaccharides were charge-fractio nated by QAE-Sephadex. The neutral oligosaccharides were further size-fract ionated by an amine absorption high performance liquid chromatography (HPLC ). Our results demonstrate that the high mannose-type oligosaccharides of h TR ranged in size from Man(5)-R to Man(9)-R with cell-type specific pattern s. A relative amount of each component was found to be differentially heter ogeneous among the four different human cell lines.