title: Subcellular localization of UDP-GlcNAc, UDP-Gal and SLC35B4 transporters.
abstract: The mechanisms of transport and distribution of nucleotide sugars in the cell remain unclear. In an attempt to further characterize nucleotide sugar transporters (NSTs), we determined the subcellular localization of overexpressed epitope-tagged canine UDP-GlcNAc transporter, human UDP-Gal transporter splice variants (UGT1 and UGT2), and human SLC35B4 transporter splice variants (longer and shorter version) by indirect immunofluorescence using an experimental model of MDCK wild-type and MDCK-RCA(r) mutant cells. Our studies confirmed that the UDP-GlcNAc transporter was localized to the Golgi apparatus only and its localization was independent of the presence of endogenous UDP-Gal transporter. After overexpression of UGT1, the protein colocalized with the Golgi marker only. When UGT2 was overexpressed, the protein colocalized with the endoplasmic reticulum (ER) marker only. When UGT1 and UGT2 were overexpressed in parallel, UGT1 colocalized with the ER and Golgi markers and UGT2 with the ER marker only. This suggests that localization of the UDP-Gal transporter may depend on the presence of the partner splice variant. Our data suggest that proteins involved in nucleotide sugar transport may form heterodimeric complexes in the membrane, exhibiting different localization which depends on interacting protein partners. In contrast to previously published data, both splice variants of the SLC35B4 transporter were localized to the ER, independently of the presence of endogenous UDP-Gal transporter.
authors.affiliation: Laboratory of Biochemistry, University of Wroclaw, Wroclaw, Poland.
authors.forename: Dorota
authors.initials: D
authors.lastname: Maszczak-Seneczko
authors.forename: Teresa
authors.initials: T
authors.lastname: Olczak
authors.forename: Mariusz
authors.initials: M
authors.lastname: Olczak
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D004285:Dogs; D004721:Endoplasmic Reticulum / Q000378:metabolism; D000939:Epitopes; D006056:Golgi Apparatus / Q000378:metabolism; D006801:Humans; D026901:Membrane Transport Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins / Q000378:metabolism*; D033704:Nucleotide Transport Proteins / Q000378:metabolism*; D020033:Protein Isoforms; D014537:Uridine Diphosphate N-Acetylglucosamine / Q000378:metabolism; D000099237:UDP-Galactose Translocators
chemical_list: D000939:Epitopes; D026901:Membrane Transport Proteins; D009004:Monosaccharide Transport Proteins; D033704:Nucleotide Transport Proteins; D020033:Protein Isoforms; D014537:Uridine Diphosphate N-Acetylglucosamine; D000099237:UDP-Galactose Translocators; C503492:SLC35B4 protein, human; C121945:UDP-N-acetylglucosamine transporter