ANALYSIS OF THE SEQUENCES OF HUMAN BETA-1,4-GALACTOSYLTRANSFERASE CDNA CLONES

作者：CHATTERJEE SK^*; MUKERJEE S; TRIPATHI PK

来源：International Journal of Biochemistry & Cell Biology, 1995, 27(3): 329-336.

DOI：10.1016/1357-2725(94)00062-G

• HUMAN GALACTOSYLTRANSFERASE
• CDNA VARIANTS
• OVARIAN TUMOR
• GENOMIC DNA CLONES
• FETAL LIVER CDNA LIBRARY

UDP-galactose:beta-1,4 N-acetyl glucosamine galactosyltransferase (4 beta GT) is a promising tumor marker for ovarian cancer. To study the role of 4 beta GT in malignant transformation at the molecular level human 4 beta GT cDNA and genomic clones were isolated and analyzed. For the isolation of 4 beta GT cDNA and genomic clones, a human fetal liver cDNA library in lambda gt11 and a human genomic library in EMBL-3B vectors respectively were screened using a 4 beta GT cDNA insert as the probe. Complete sequence of the cDNA clones were determined by subcloning in plasmid vectors, and compared with the published sequence of human liver 4 beta GT. Presence of various 4 beta GT exons in the genomic clones were determined by Southern blot analysis using specific oligodeoxynucleotide probes. Among the 5 cDNA clones isolated, 2 clones GTN 6 and GTN 17 were sibling clones and had a nucleotide sequence identical to the published 4 beta GT cDNA sequence, except at the 3'-end, where these clones had 7 unique nucleotide sequences. One cDNA clone, GTN2 also had a nucleotide sequence identical to that of 4 beta GT, except for 3 G residues at the 5'-end. One cDNA clone, GTN 1, had a unique sequence at the 5'-end comprising of 74 nucleotides. Another clone, GTN 20, was unrelated to 4 beta GT. Analysis of genomic clones showed that 4 beta GT exons 3, 4, 5 and 6 were present in a 14 kb genomic clone, EMGT-4. Exon 1 was present in a separate 16 kb clone, EMGT-6. No clone was detected for exon 2. Southern blot analysis and partial restriction mapping of EMGT-6 showed that the 74 nucleotide unique sequence of GTN1 was present in this genomic clone. But this DNA fragment has separated from exon 1 by a distance of about 10 kb. This study showed that human 4 beta GT cDNA had divergent sequences, both at the 5'- and 3'-ends. Among them, a 74 nucleotide unique sequence at the 5'-end of GTN1 is present along with exon 1 in a genomic clone. It is proposed that the divergent cDNA clones represent various isoenzymes of 4 beta GT found in normal and malignant cells.

• 出版日期1995-3