A novel β(1,6)‐N‐acetylglucosaminyltransferase V (GnT‐VB)

FEBS Letters

Pierce, Michael¹  Alvarez-Manilla, Gerardo¹  Troupe, Karolyn¹  Zhang, Wei-jie³  Lee, Intaek¹  Kaneko, Mika¹  Kamar, Maria¹  Lee, Jin-Kyu¹  Osawa, Motoki² 

[1] Complex Carbohydrate Research Center and Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30605, USA;Department of Experimental and Forensic Pathology, Yamagata University School of Medicine, 2-2-2 Iida-Nishi, Yamagata 990-9585, Japan;College of Biological Science and Technology, Shanghai Jiao Tong University, Shanghai, PR China

关键词: Glycosyltransferase;    UDP-N-acetylglucosamine:α(1;    6)-D-mannoside β(1;    6)-N-acetylglucosaminyltransferase;    L-Phytohemagglutinin;    N-Linked β(1;    6) branch;    GnT-V;    UDP-N-acetylglucosamine:α(1;    6)-D-mannoside β(1;    6)-N-acetylglucosaminyltransferase;    L-PHA;    L-phytohemagglutinin;    GlcNAc;    N-acetylglucosamine;    Man;    mannose;    Gal;    galactose;    EST;    expressed sequence tag;    ORF;    open reading frame;    PCR;    polymerase chain reaction;    G3PDH;    glyceraldehyde-3-phosphate dehydrogenase;    MALDI-TOF;    matrix-assisted laser desorption/ionization-time of flight;   

DOI  :  10.1016/S0014-5793(03)01234-1

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

UDP-N-acetylglucosamine:α(1,6)-D-mannoside β(1,6)-N-acetylglucosaminyltransferase (GnT-V, Mgat5) functions in the biosynthesis of N-linked glycans and is transcriptionally upregulated by oncogene signaling. We report here the cloning and characterization of a human cDNA encoding a distinct enzyme with related substrate specificity, termed GnT-VB, which is predicted to have 53% similarity to the original amino acid sequence of GnT-V(A). Transient expression of GnT-VB cDNA in COS7 cells yielded significant increases of activity toward GnT-VA acceptors, including synthetic saccharides and N-linked glycopeptides, with some differences in specificity. Unlike GnT-VA, GnT-VB required divalent cation for full activity. EST databases showed expression of a 6 bp (+) splice isoform of GnT-VB; when expressed, this enzyme showed significantly reduced activity. CHO Lec4 cells, which do not express GnT-VA or B activity, lack synthesis of the N-linked β(1,6) branch, and do not bind L-phytohemagglutinin (L-PHA), were transfected with GnT-VB or GnT-VA; both then bound significant amounts of L-PHA, demonstrating that both enzymes synthesized N-linked β(1,6) branched glycans in vivo. Real-time polymerase chain reaction results showed that GnT-VB mRNA was highly expressed in brain and testis, with lesser levels in other tissues, while human GnT-VA showed a more general expression, but with low levels in brain and no expression in skeletal muscle.

【 授权许可】

Unknown