Molecular cloning of the hamster CMP-sialic acid transporter.
Chinese hamster ovary (CHO) glycosylation mutants of the Lec2 complementation group are unable to express sialylated glycoproteins and glycolipids due to a defect in the Golgi CMP-sialic acid transporter (CMP-Sia-Tr). Using an expression cloning strategy, we isolated a cDNA encoding the hamster CMP-Sia-Tr which complements the Lec2 phenotype. The deduced amino acid sequence of the cloned cDNA shows 95% identity to the recently cloned murine CMP-Sia-Tr. The expression of a hamster CMP-Sia-Tr fusion protein with an N-terminal MDYKDDDDK (FLAG) sequence revealed Golgi localisation of the transporter. Amino acid sequence comparison revealed strong similarity (44.6% identity and 19.3% similarity) of CMP-Sia-Tr to the recently cloned human UDP-galactose transporter (UDP-Gal-Tr). In contrast, sequence similarities to the yeast UDP-N-acetylglucosamine transporter (UDP-GlcNAc-Tr) and the GDP-mannose transporter (GDP-Man-Tr) of Leishmania donovani are restricted to a region encoding the two most C-terminally located transmembrane helices. A computer-based structural analysis of CMP-Sia-Tr proposes an eight transmembrane helix model with the N- and C-termini located on the cytosolic side of the Golgi membrane.
Eckhardt
M
M
Institut für Medizinische Mikrobiologie, Medizinische Hochschule Hannover, Germany.
Gerardy-Schahn
R
R
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D016466:CHO Cells; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D003001:Cloning, Molecular; D006224:Cricetinae; D003568:Cytidine Monophosphate / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D000939:Epitopes / Q000235:genetics; D006031:Glycosylation; D006056:Golgi Apparatus / Q000378:metabolism; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009154:Mutation; D019158:N-Acetylneuraminic Acid / Q000378:metabolism; D033704:Nucleotide Transport Proteins; D016133:Polymerase Chain Reaction; D017433:Protein Structure, Secondary; D017386:Sequence Homology, Amino Acid
D002352:Carrier Proteins; D017931:DNA Primers; D000939:Epitopes; D008565:Membrane Proteins; D033704:Nucleotide Transport Proteins; C491081:SLC35A1 protein, human; D003568:Cytidine Monophosphate; D019158:N-Acetylneuraminic Acid