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The intranucleolar distribution of phosphoproteins B23 and C23 was visualized simultaneously by post-embedding immunoelectron microscopy in HeLa cell nucleoli, using specific antibodies. The data show that proteins B23 and C23 co-localize to the same nucleolar compartments, i.e., the dense fibrillar component and the granular component. Neither of the two(More)
Two distinct but related groups of cDNA clones, CKbeta4GT-I and CKbeta4GT-II, have been isolated by screening a chicken hepatoma cDNA library with a bovine beta1,4-galactosyltransferase (beta4GT) cDNA clone. CKbeta4GT-I is predicted to encode a type II transmembrane glycoprotein of 41 kDa with one consensus site for N-linked glycosylation. CKbeta4GT-II is(More)
The cross-linking of the two components of lactose synthetase, alpha-lactalbumin and a galactosyltransferase, with dimethylpimelimidate was examined. The extent of the cross-linking at pH 8.1 was found to be dependent upon the presence of substrates or inhibitors for the galactosyltransferase. N-acetylglucosamine and mixtures of either N-acetylglucosamine,(More)
Beta 1,4-galactosyltransferase (beta 1,4-GT) is a Golgi-resident, type II membrane-bound glycoprotein that functions in the coordinate biosynthesis of complex oligosaccharides. Additionally, beta 1,4-GT has been localized to the cell surface of a variety of cell types and tissues where it is proposed to function in intercellular recognition and/or adhesion.(More)
UDP-Gal:Gal beta 1----4GlcNAc alpha 1----3-galactosyltransferase is a terminal glycosyltransferase that is widely expressed in a variety of mammalian species, with the notable exception of man, apes, and Old World monkeys. We recently reported the isolation of a bovine cDNA clone that contains the complete coding sequence for this enzyme (Joziasse, D. H.,(More)
beta1,4-Galactosyltransferase (beta4-GT) is a constitutively expressed enzyme that synthesizes the beta4-N-acetyllactosamine structure in glycoconjugates. In mammals, beta4-GT has been recruited for a second biosynthetic function, the production of lactose which occurs exclusively in the lactating mammary gland. In somatic tissues, the murine beta4-GT gene(More)
Past studies from this laboratory have suggested that mouse sperm binding to the egg zona pellucida is mediated by a sperm galactosyltransferase (GalTase), which recognizes and binds to terminal N-acetylglucosamine (GlcNAc) residues in the zona pellucida (Shur, B. D., and N. G. Hall, 1982, J. Cell Biol. 95:567-573; 95:574-579). We now present evidence that(More)
The beta 1,4-galactosyltransferase (beta 1,4-GT) gene is unusual in that it specifies two mRNAs in somatic cells of 3.9 and 4.1 kilobases (kb). These two transcripts arise as a consequence of initiation at two different sets of start sites that are separated by approximately 200 base pairs. Translation of each mRNA results in the predicted synthesis of two(More)
The intracellular distribution of nucleolar phosphoproteins B23 and nucleolin was studied during mouse spermatogenesis, a process that is characterized by a progressive reduction of nucleolar activity. Biochemical analyses of isolated germ cell fractions were performed in parallel with the in situ ultrastructural immunolocalization of these two proteins by(More)
alpha1,3-galactosyltransferase (alpha3GalT, EC 2.4.1.151) is a Golgi-resident, type II transmembrane protein that transfers galactose from UDP-alpha-galactose to the terminal N:-acetyllactosamine unit of glycoconjugate glycans, producing the Galalpha1,3Galbeta1,4GlcNAc oligosaccharide structure present in most mammalian glycoproteins. Unlike most other(More)