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

Citation
Sk. Chatterjee et al., ANALYSIS OF THE SEQUENCES OF HUMAN BETA-1,4-GALACTOSYLTRANSFERASE CDNA CLONES, International journal of biochemistry & cell biology, 27(3), 1995, pp. 329-336
Citations number
32
Categorie Soggetti
Biology
ISSN journal
13572725
Volume
27
Issue
3
Year of publication
1995
Pages
329 - 336
Database
ISI
SICI code
1357-2725(1995)27:3<329:AOTSOH>2.0.ZU;2-J
Abstract
UDP-galactose:beta-1,4 N-acetyl glucosamine galactosyltransferase (4 b eta GT) is a promising tumor marker for ovarian cancer. To study the r ole of 4 beta GT in malignant transformation at the molecular level hu man 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 live r cDNA library in lambda gt11 and a human genomic library in EMBL-3B v ectors respectively were screened using a 4 beta GT cDNA insert as the probe. Complete sequence of the cDNA clones were determined by subclo ning in plasmid vectors, and compared with the published sequence of h uman liver 4 beta GT. Presence of various 4 beta GT exons in the genom ic clones were determined by Southern blot analysis using specific oli godeoxynucleotide probes. Among the 5 cDNA clones isolated, 2 clones G TN 6 and GTN 17 were sibling clones and had a nucleotide sequence iden tical 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, ex cept for 3 G residues at the 5'-end. One cDNA clone, GTN 1, had a uniq ue 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 cl one, 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 rest riction mapping of EMGT-6 showed that the 74 nucleotide unique sequenc e 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'- an d 3'-ends. Among them, a 74 nucleotide unique sequence at the 5'-end o f 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.