Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.3.1.28 (chloramphenicol acetyltransferase)
 5,100 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

UDP-GlcNAc:alpha-6-D-mannoside beta-1,2-N-acetylglucosaminyltransferase II (GnT II; EC 2.4.1.143) is essential for the normal assembly of complex Asn-linked glycans. Northern analysis showed a major transcript at 2.0 kb and a minor band at approximately 2.9 kb in five different human cell lines. The gene (MGAT2) has three AATAAA polyadenylation sites at 68, 688 and 846 bp downstream of the translation stop codon. 3'-RACE (rapid amplification of cDNA ends) using RNA from the human cell line LS-180 indicated that all three sites were utilized for transcription termination. 5'-RACE and RNase protection analyses showed multiple transcription initiation sites at -440 to -489 bp relative to the ATG translation start codon (+1). The data show that the entire GnT II gene is on a single exon. The gene has a CCAAT box at -587 bp but lacks a TATA box and the 5'-untranslated region is GC-rich and contains consensus sequences suggestive of multiple binding sites for Sp1; these properties are typical for housekeeping genes. A series of chimeric constructs containing different lengths of the 5'-untranslated region fused to the chloramphenicol acetyltransferase (CAT) reporter gene were tested in transient transfection experiments using HeLa cells. The CAT activity of the construct containing the longest insert (-1076 bp relative to the ATG start codon) showed a approximately 38-fold increase as compared to that of the control. Removal of the region between -636 and -553 bp caused a dramatic decrease in CAT activity indicating this to be the main promoter region of the gene.
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PMID:Transcriptional regulation of the human UDP-GlcNAc:alpha-6-D-mannoside beta-1-2-N-acetylglucosaminyltransferase II gene (MGAT2) which controls complex N-glycan synthesis. 957 8

The X protein of hepatitis B virus (HBx) plays a major role on hepatocellular carcinoma (HCC). Apolipoprotein B (apoB) in the liver is an important glycoprotein for transportation of very low density lipoproteins and low density lipoproteins. Although lipid accumulation in the liver is known as one of the factors for the HCC, the relationship between HBx and apoB during the HCC development is poorly understood. To better understand the biological significance of HBx in HCC, liver Chang cells that specifically express HBx were established and characterized. In this study we demonstrate that overexpression of HBx significantly up-regulates the expression of UDP-N-acetylglucosamine:beta-d-mannoside-1,4-N-acetylglucosaminyltransferase-III (GnT-III), an enzyme that functions as a bisecting-N-acetylglucosamine (GlcNAc) transferase in apoB, and increases GnT-III promoter activity in a chloramphenicol acetyltransferase assay. GnT-III expression levels of HBx-transfected cells appeared to be higher than that of hepatocarcinoma cells as well as GnT-III-transfected cells, indicating that HBx may has a strong GnT-III promotor-enhancing activity. Intracellular levels of apoBs, which contained the increased bisecting GlcNAc, were accumulated in HBx-transfected liver cells. These cells as well as GnT-III-transfected liver cells revealed the inhibition of apoB secretion and the increased accumulation of intracellular triglyceride and cholesterol compared with vector-transfected cells. Moreover, overexpression of GnT-III and HBx in liver cells was shown to down-regulate the transcriptional level of microsomal triglyceride transfer protein, which regulates the assembly and secretion of apoB. Therefore, our study strongly suggested that the HBx increase in intracellular accumulation of aberrantly glycosylated apoB resulted in inhibition of secretion of apoB as well as intracellular lipid accumulation by elevating the expression of GnT-III.
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PMID:The hepatitis B virus X protein inhibits secretion of apolipoprotein B by enhancing the expression of N-acetylglucosaminyltransferase III. 1512 6