The transmembrane and flanking sequences of β1,2 N-acetylglucosaminyltransferase I specify medial-golgi localization

Abstract

UDP-GlcNAc:α3-D-mannoside β1,2-N-acetylglucosaminyltransferase I (GnTI) is an Nin/Cout (type II) membrane protein, localized in the medial-Golgi, that initiates the conversion of high mannose N-glycans to complex N-glycans. Anti-rabbit GnTI antibodies were generated using a purified, enzymatically active, bacterial recombinant fusion protein as immunogen. Rabbit GnTI was effectively retained in the Golgi complex of transfected COS-1 cells and murine L cells, as assessed by indirect immunofluorescence using the species-specific anti-GnTI antibodies; no surface expression of rabbit GnTI could be detected in the transfected cells. Rabbit GnTI, stably expressed in murine L cells, was localized b..