Two active and differently N-glycosylated isoforms of human ST3Gal-V are produced from the placental mRNA variant by a leaky scanning mechanism.
Previously, we identified a human ST3Gal-V mRNA variant peculiarly characterized by the presence of a translational start codon localized up-stream and in-frame with the one that is usually considered as unique translation initiation site in the human gene. In this study we demonstrate, by cDNA transfection experiments, mutational analyses, enzyme activity assays, and endoglycosidase-H treatments, that the in vivo expression of this transcript gives rise to two human ST3Gal-V isoforms with distinct characteristics. Produced by a leaky scanning mechanism, they carry different N-glycan structures and exhibit differences in their GM(3) synthase activity that might be relevant for the modulation of GM(3) cellular content.
Zava
Stefania
S
Università degli Studi di Milano, Dipartimento di Scienze Molecolari Applicate ai Biosistemi, Milan, Italy.
Milani
Simona
S
Sottocornola
Elena
E
Berra
Bruno
B
Colombo
Irma
I
D015153:Blotting, Western; D004720:Endonucleases / Q000378:metabolism; D005260:Female; D005679:G(M3) Ganglioside / Q000378:metabolism; D014644:Genetic Variation; D006031:Glycosylation; D006801:Humans; D007527:Isoenzymes / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D010920:Placenta / Q000378:metabolism*; D011134:Polysaccharides / Q000737:chemistry / Q000378:metabolism; D011247:Pregnancy; D012333:RNA, Messenger / Q000235:genetics; D012799:Sialyltransferases / Q000096:biosynthesis* / Q000737:chemistry* / Q000378:metabolism; D013379:Substrate Specificity
D005679:G(M3) Ganglioside; D007527:Isoenzymes; D011134:Polysaccharides; D012333:RNA, Messenger; D012799:Sialyltransferases; C021343:haematoside synthetase; D004720:Endonucleases; D009584:Nitrogen