A disulfide-bonded dimer of the Golgi beta-galactoside alpha 2,6-sialyltransferase is catalytically inactive yet still retains the ability to bind galactose

被引:67
作者
Ma, JY [1 ]
Colley, KJ [1 ]
机构
[1] UNIV ILLINOIS,COLL MED,DEPT BIOCHEM,CHICAGO,IL 60612
关键词
D O I
10.1074/jbc.271.13.7758
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
The alpha 2,6-sialyltransferase is a terminal glycosyltransferase localized in the trans Golgi and trans Golgi network. Here we show that 30% of the total rat liver Golgi alpha 2,6-sialyltransferase forms a disulfide-bonded 100-kDa species that can be converted to the 50-kDa monomer form of the enzyme upon reduction. Limited proteolysis of both enzyme forms demonstrates that the 100-kDa species is a disulfide-bonded homodimer of the alpha 2,6-sialyltransferase. The alpha 2,6-sialyltransferase disulfide-bonded dimer is found in bovine liver Golgi membranes and in Golgi membranes prepared and solubilized in the presence of 100 mM iodoacetamide, suggesting that it is not unique to rat liver or formed aberrantly upon membrane lysis. The dimer form of the enzyme possesses no significant catalytic activity and has a much lower affinity for CDP-hexanolamine-agarose compared with the monomer form. In contrast, both the alpha 2,6-sialyltransferase monomer and the disulfide-bonded dimer bind strongly to galactose and galactose-terminated substrates. These results suggest that the alpha 2,6-sialyltransferase disulfide-bonded dimer lacks catalytic activity due to a weak affinity for its sugar nucleotide donor, CMP-NeuAc, and that this catalytically inactive form of the enzyme may act as a galactose-specific lectin in the Golgi.
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页码:7758 / 7766
页数:9
相关论文
共 52 条
[1]   PURIFICATION AND PROPERTIES OF NEURAMINIDASE FROM VIBRIO CHOLERAE [J].
ADA, GL ;
LIND, PE ;
FRENCH, EL .
JOURNAL OF GENERAL MICROBIOLOGY, 1961, 24 (03) :409-&
[2]   GOLGI RETENTION OF A TRANS-GOLGI MEMBRANE-PROTEIN, GALACTOSYL-TRANSFERASE, REQUIRES CYSTEINE AND HISTIDINE-RESIDUES WITHIN THE MEMBRANE-ANCHORING DOMAIN [J].
AOKI, D ;
LEE, N ;
YAMAGUCHI, N ;
DUBOIS, C ;
FUKUDA, MN .
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 1992, 89 (10) :4319-4323
[3]   BIOSYNTHESIS AND INTRACELLULAR-TRANSPORT OF ALPHA-2,6-SIALYLTRANSFERASE IN RAT HEPATOMA-CELLS [J].
BOSSHART, H ;
BERGER, EG .
EUROPEAN JOURNAL OF BIOCHEMISTRY, 1992, 208 (02) :341-349
[4]   CHOLESTEROL AND THE GOLGI-APPARATUS [J].
BRETSCHER, MS ;
MUNRO, S .
SCIENCE, 1993, 261 (5126) :1280-1281
[5]  
BURKE J, 1994, J BIOL CHEM, V269, P12049
[6]   REGULATION OF PROTEIN-SYNTHESIS BY HEME-REGULATED EIF-2-ALPHA KINASE [J].
CHEN, JJ ;
LONDON, IM .
TRENDS IN BIOCHEMICAL SCIENCES, 1995, 20 (03) :105-108
[7]  
CLEVELAND DW, 1977, J BIOL CHEM, V252, P1102
[8]  
COLLEY KJ, 1989, J BIOL CHEM, V264, P17619
[9]  
COLLEY KJ, 1992, J BIOL CHEM, V267, P245
[10]  
DAHDAL RY, 1993, J BIOL CHEM, V286, P26310