Cell-specific expression of human beta-galactoside alpha 2,6-sialyltransferase transcripts differing in the 5' untranslated region.
In humans, two cDNAs have been isolated encoding beta-galactoside alpha 2,6-sialyltransferase, differing only in part of the 5' untranslated region. Primer extension data show that the two cDNAs are near full-length clones. RNase protection analysis of different cell types showed that the transcript corresponding to the alpha 2,6-sialyltransferase cDNA isolated from a B-cell library resided only in mature B cells. In contrast, the transcript corresponding to the alpha 2,6-sialyltransferase cDNA isolated from a placenta library was found in all cells tested. Our results also indicate the existence of a third alpha 2,6-sialyltransferase transcript in the hepatoma cell line HepG2. Mature B cells were found to express high amounts of alpha 2,6-sialyltransferase mRNA, compared to other cell types tested, as shown by Northern blot analysis. Moreover there was an increased expression of beta-galactoside alpha 2,6-sialyltransferase mRNA in activated B cells compared to resting B cells. In vitro transcription and translation of the cDNAs resulted in a protein of 45 kDa, but the transcripts were translated with different efficiency, suggesting a role for the 5' untranslated region in regulation of translation. We have also made an alpha 2,6-sialyltransferase construct lacking the specific 5' regions of the two cDNAs. A transcript generated from this construct was translated more efficiently in vitro than the two alpha 2,6-sialyltransferase cDNAs.
Aasheim
H C
HC
Department of Immunology, Norwegian Radium Hospital, Oslo.
Aas-Eng
D A
DA
Deggerdal
A
A
Blomhoff
H K
HK
Funderud
S
S
Smeland
E B
EB
D001402:B-Lymphocytes / Q000378:metabolism; D001483:Base Sequence; D015152:Blotting, Northern; D002460:Cell Line; D004247:DNA; D015870:Gene Expression; D006801:Humans; D007438:Introns; D008099:Liver / Q000378:metabolism; D008969:Molecular Sequence Data; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid; D012799:Sialyltransferases / Q000096:biosynthesis / Q000235:genetics*; D014407:Tumor Cells, Cultured; D000094802:beta-D-Galactoside alpha 2-6-Sialyltransferase
D012333:RNA, Messenger; D004247:DNA; D012799:Sialyltransferases; D000094802:beta-D-Galactoside alpha 2-6-Sialyltransferase