Role of galactosyl-transferases in rat gastric epithelial glycoprotein synthesis

Strous, Ger J.; Hendriks, Henno; Kramer, M. F.

doi:10.1016/0005-2744(80)90092-3

Cited by 12 publications

(3 citation statements)

References 30 publications

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“…The (1-*4)and (1-+3)-transferases have different optimal requirements for Mn2+: the (1-4)-transferase is most active at 15mM, whereas the (1-*3)transferase is most active at 5-10mM. These results correspond precisely to those previously obtained with rat liver enzymes (Strous et al, 1980). Subsequent assays were therefore conducted with 15mM-MnCl2 for the (1-4)-transferase and with lOmM-MnCl2 for the (1-*3)-transferase.…”

Section: Effect Of Mn2+ and Ph On Galactosyltransferasessupporting

confidence: 87%

Co-purification of galactosyltransferases from chick-embryo liver

Furukawa¹,

Roth²

1985

Biochemical Journal

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Two galactosyltransferases with nearly identical Mr values were purified 5000-7000-fold from microsomal membranes of chick-embryo livers by using several affinity columns. One enzyme transfers galactose from UDP-galactose to form a beta-(1----4)-linkage to GlcNAc (N-acetylglucosamine) or AsAgAGP [asialo-agalacto-(alpha 1-acid glycoprotein)]. The other enzyme forms a beta-(1----3)-linkage to AsOSM [asialo-(ovine submaxillary mucin)]. Both enzymes were solubilized (85%) from a microsomal pellet by using 1% Triton X-100 in 0.1 M-NaCl. The supernatant activities were subjected to DEAE-Sepharose chromatography and four affinity columns: UDP-hexanolamine-Sepharose, alpha-lactalbumin-Sepharose, GlcNAc-Sepharose and either AsAgAGP-Sepharose or AsOSM-Sepharose. The AsAgAGP enzyme [(1----4)-transferase] and the AsOSM enzyme [(1----3)-transferase] behave identically on the DEAE-Sepharose and UDP-hexanolamine-Sepharose columns, and similarly on the alpha-lactalbumin-Sepharose column. Final separation of the two enzymes, however, could only be achieved on affinity columns of their immobilized respective acceptors. Both purified enzymes migrate as a single band on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis after silver staining, and both have an apparent Mr of 68 000. The enzymes were radioiodinated and again subjected to sodium dodecyl sulphate/polyacrylamide-gel electrophoresis. Radioautographic analyses showed only one, intensely radioactive, band. Activity stains performed for both transferases after cellulose acetate electrophoresis indicate that, with this system too, both activities have identical mobilities, and co-migrate, as well, with the major, silver-stained, protein band. Kinetic studies with the purified enzymes show that the Km value for GlcNAc, for the (1----4)-transferase, is 4mM; for the (1----3)-transferase the Km value for AsOSM is 5mM, in terms of GalNAc (N-acetylgalactosamine) equivalents. Both enzymes have a Km value of 25 microM for UDP-galactose.

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Section: Effect Of Mn2+ and Ph On Galactosyltransferasessupporting

confidence: 87%

Co-purification of galactosyltransferases from chick-embryo liver

Furukawa¹,

Roth²

1985

Biochemical Journal

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“…Galactosyltransférase is able to transfer galactose to endogenous acceptors [1,15,18]. The findings in this paper obtained with preparations from a human urinary tumor cell line and from rat liver microsomes dem onstrate that Co2+ can completely substitute for Mn2+ in both endogenous galactosyltransferase reactions.…”

Section: Endogenous Galactosylationmentioning

confidence: 59%

“…As recently reported, urinary bladder tumor cells are able to galactosylate endoge nous acceptors [1]. Strous et al [15] reported galactose transfer to endogenous acceptors in microsomal fractions derived from rat stomach.…”

Section: Endogenous Galactosylationmentioning

confidence: 75%

Co^2+ Is Able to Substitute for Mn^2+ in Some Exogenous and Endogenous Galactosyltransférase Reactions

Gmeiner¹

1988

Enzyme

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The ability of Co^2+ to substitute for Mn^2+ in exogenous and endogenous galactosyltransférase reactions was tested. Exogenous transfer was measured towards different high and low molecular weight galactose acceptors using galactosyltransférase from the following sources: crude serum, the serum enzyme partially purified by affinity chromatography and a pure enzyme preparation from milk. Endogenous transfer was estimated in preparations from human urinary bladder tumor cells and from rat liver microsomal fractions. The results show that Co^2+ is able to substitute for Mn^2+ in some exogenous and endogenous galactosyltransférase reactions. This ability seems to depend on the molecular structure of the galactose acceptor as well as on the nature of the enzyme.

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