Complete cDNA sequence encoding human β-galactoside α-2, 6-sialyltransferase

Grundmann, U.; Nerlich, Claudia; Rein, Theo; Zettlmeissl, Gerd

doi:10.1093/nar/18.3.667

Cited by 135 publications

(52 citation statements)

References 2 publications

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“…NeuAc␣2,3Gal␤1,3GalNAc GalNAc␣2,6-Sialyltransferaseof the ST8Sia family (21, 25, 26, 37, 44 -54) 5 or ST6Gal I (55)(56)(57)(58)(59). 6 This indicates that one ST6GalNAc subfamily (I and II) and the ST3Gal family, but not another one (III and IV), share common domain structures.…”

Section: Discussionmentioning

confidence: 99%

Molecular Cloning and Functional Expression of Two Members of Mouse NeuAcα2,3Galβ1,3GalNAc GalNAcα2,6-Sialyltransferase Family, ST6GalNAc III and IV

Lee¹,

Kaufmann²,

Kitazume-Kawaguchi³

et al. 1999

Journal of Biological Chemistry

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Two cDNA clones encoding NeuAc␣2,3Gal␤1,3GalNAc GalNAc␣2,6-sialyltransferase have been isolated from mouse brain cDNA libraries. One of the cDNA clones is a homologue of previously reported rat ST6GalNAc III according to the amino acid sequence identity (94.4%) and the substrate specificity of the expressed recombinant enzyme, while the other cDNA clone includes an open reading frame coding for 302 amino acids. The deduced amino acid sequence is not identical to those of other cloned mouse sialyltransferases, although it shows the highest sequence similarity with mouse ST6GalNAc III (43.0%). The expressed soluble recombinant enzyme exhibited activity toward NeuAc␣2, 3Gal␤1,3GalNAc, fetuin, and GM1b, while no significant activity was detected toward Gal␤1,3GalNAc or asialofetuin, or the other glycoprotein substrates tested. The sialidase sensitivity of the 14 C-sialylated residue of fetuin, which was sialylated by this enzyme with CMP-[ 14 C]NeuAc, was the same as that of ST6GalNAc III. These results indicate that the expressed enzyme is a new type of GalNAc␣2,6-sialyltransferase, which requires sialic acid residues linked to Gal␤1,3GalNAc residues for its activity; therefore, we designated it mouse ST6GalNAc IV. Although the substrate specificity of this enzyme is similar to that of ST6GalNAc III, ST6GalNAc IV prefers O-glycans to glycolipids. Glycolipids, however, are better substrates for ST6GalNAc III.Sialic acids are key determinants of carbohydrate structures that play important roles in a variety of biological functions, like cell-cell communication, cell-substrate interaction, adhesion, and protein targeting. The transfer of sialic acids from CMP-Sia 1 to the terminal positions of the carbohydrate groups of glycoproteins and glycolipids is catalyzed by a sialyltransferase. Although roles of sialic acids have been proposed in the regulation of many biological phenomena, the purpose of this structural diversity remains largely obscure. To determine the meaning of the diversity of and the regulatory mechanism for the sialylation of glycoconjugates, it is necessary to obtain information on the enzymes themselves and the gene structure of sialyltransferases. Each sialyltransferase exhibits strict specificity for acceptor substrates and linkages (3-6). Although three linkages, Sia␣2,6Gal, Sia␣2,3Gal, and Sia␣2,6GalNAc, are commonly found in glycoproteins (7), and two, Sia␣2,3Gal and Sia␣2,8Sia, occur frequently in gangliosides (8), each of these linkages has been found in both gangliosides and glycoproteins (8 -10).So far, the cloning of three members of the ␣2,6-sialyltransferase family (ST6GalNAc I, II and III) has been reported (11-14). The cDNAs of ST6GalNAc I and II were cloned from both chick (11, 12) and mouse (13,62).2 The overall amino acid sequence identity of chick ST6GalNAc I is 30.5% to chick ST6GalNAc II, 43.2% to mouse ST6GalNAc I, and 33.6% to mouse ST6GalNAc II, and that of mouse ST6GalNAc I is 29.6% to mouse ST6GalNAc II and 28.3% to chick ST6GalNAc II, and that of chick ST6GalNAc II is 57.3% ...

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Section: Discussionmentioning

confidence: 99%

Molecular Cloning and Functional Expression of Two Members of Mouse NeuAcα2,3Galβ1,3GalNAc GalNAcα2,6-Sialyltransferase Family, ST6GalNAc III and IV

Lee¹,

Kaufmann²,

Kitazume-Kawaguchi³

et al. 1999

Journal of Biological Chemistry

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“…To answer the questions whether the signals for Golgi targeting and retention are recognized in yeast, we chose to investigate ST. This enzyme is thoroughly characterized in terms of molecular (Weinstein et al, 1987;Grundmann et al, 1990) and cell biology as well as for its enzymic properties (Paulson et al, 1977;Weinstein et al, 1982). For comparison, we also included data on rGT and take advantage of the fact that the yeast Golgi apparatus lacks both enzymes.…”

Section: Discussionmentioning

confidence: 99%

Human β1,4 galactosyltransferase and α2,6 sialyltransferase expressed in Saccharomyces cerevisiae are retained as active enzymes in the endoplasmic reticulum

Krezdorn¹,

Kleene²,

Watzele³

et al. 1994

European Journal of Biochemistry

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Biosynthesis and intracellular transport of recombinant human full-length Pl,4 galactosyltransferase (GT) and full-length a2,6 sialyltransferase (ST) were investigated in Saccharomyces cerevisiae. Recently, enzymic activity of recombinant GT (rGT) in crude homogenates of S. cerevisiae could successfully be demonstrated [Krezdorn, C . , Watzele, G., Kleene, R. B., Ivanov, S. X. & Berger, E. G. (1993) Eur: J. Biochem. 212, 113-1201. In the present work, we show that, in yeast strains transformed with plasmid pDPSIA containing the cDNA coding for human ST, rST enzymic activity using asialo-fetuin or N-acetyllactosamine as acceptor substrates could readily be detected. Analysis by 'H-NMR spectroscopy of the disaccharide product of rGT, as recently reported, and the trisaccharide product of rST demonstrated that only the expected glycosidic linkages were formed. Following mechanical disruption of yeast cells, both enzymes sedimented with a fraction enriched in membranes of the endoplasmic reticulum (ER) and were activated by Triton X-100 3-5-fold. rGT and rST could be immunoprecipitated from their [35S]Met-labelled transformed yeast extracts using polyclonal antibodies raised against fusion proteins consisting of P-galactosidase-GT or P-galactosidase-ST, respectively, expressed in Escherichia coli. For rGT a single glycosylated form of apparent molecular mass 48 kDa was reported, but for rST two main bands corresponding to apparent molecular masses of 48 kDa and 44 kDa, respectively, were detected. Immunoprecipitation from either tunicamycin-treated [35S]Met-labelled transformed yeast cells or labelling with radioactive sugars both indicated that the 44-kDa form of rST was non-glycosylated and that the 48-kDa form of rST was core N-glycosylated. In addition, core glycosylation of both recombinant enzymes demonstrated that they were competent for translocation across the ER membranes. However, the 44-kDa form of rST was converted to the 48-kDa glycosylated form only slowly, suggesting a mechanism of posttranslational translocation. Absence of hyperglycosylation of rST and rGT in wild type and lack of the Golgi-specific man-al,6-man epitope suggest that the recombinant enzymes did not enter the yeast Golgi apparatus.These results indicated that both rGT and rST are retained as enzymically active enzymes in the ER of yeast and suggest a ribonucleoprotein-independent import of rST into the ER.

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“…To date, 2 members of the ST6Gal family, ST6Gal-I and -II, have been identified in mammals (62)(63)(64)(65)(66)(67)(68)(69). These enzymes commonly utilize the Galβ1,4GlcNAc structure on glycoproteins and oligosaccharides as an acceptor substrate.…”

Section: Functions Of the St6gal Family Membersmentioning

confidence: 99%