Golgi localization and in vivo activity of a mammalian glycosyltransferase (human beta1,4-galactosyltransferase) in yeast.
J Biol Chem
; 271(7): 3398-405, 1996 Feb 16.
Article
em En
| MEDLINE
| ID: mdl-8631939
ABSTRACT
Gene fusions encoding the membrane anchor region of yeast alpha1, 2-mannosyltransferase (Mnt1p) fused to human beta1, 4-galactosyltransferase (Gal-Tf) were constructed and expressed in the yeast Saccharomyces cerevisiae. Fusion proteins containing 82 or only 36 N-terminal residues of Mnt1p were produced and quantitatively N-glycosylated; glycosyl chains were shown to contain alpha1,6-, but not alpha1,3-mannose determinants, a structure typical for an early Golgi compartment. A final Golgi localization of both fusions was confirmed by sucrose gradient fractionations, in which Gal-Tf activity cofractionated with Golgi Mnt1p activity, as well as by immunocytological localization experiments using a monoclonal anti-Gal-Tf antibody. In an in vitro Gal-Tf enzymatic assay the Mnt1/Gal-Tf fusion and soluble human Gal-Tf had comparable Km values for UDP-Gal (about 45 microM). To demonstrate in vivo activity of the Mnt1/Gal-Tf fusion the encoding plasmids were transformed in an alg1 mutant, which at the non-permissive temperature transfers short (GlcNAc)2 glycosyl chains to proteins. Using specific lectins the addition of galactose to several yeast proteins in transformants could be detected. These results demonstrate that Gal-Tf, a mammalian glycosyltransferase, is functional in the molecular environment of the yeast Golgi, indicating conservation between yeast and human cells. The in vivo function of human Gal-Tf indicates that the yeast Golgi is accessible for UDP-Gal and suggests strategies for the construction of yeast strains, in which desired glycoforms of heterologous proteins are produced.
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Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
N-Acetil-Lactosamina Sintase
/
Complexo de Golgi
Limite:
Animals
/
Humans
Idioma:
En
Revista:
J Biol Chem
Ano de publicação:
1996
Tipo de documento:
Article
País de afiliação:
Alemanha