Medial-Golgi retention of N-acetylglucosaminyltransferase I. Contribution from all domains of the enzyme
We have previously shown that the transmembrane domain and flanking residues of beta-1,2-N-acetylglucosaminyltransferase I (GnTI) can localize a hybrid molecule to medial-Golgi cisternae (Burke, J., Pettitt, J. M., Schachter, H., Sarkar, M., and Gleeson, P.A. (1992) J. Biol. Chem. 267, 24433-24440)....
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Published in | The Journal of biological chemistry Vol. 269; no. 16; pp. 12049 - 12059 |
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Main Authors | , , , |
Format | Journal Article |
Language | English |
Published |
Bethesda, MD
American Society for Biochemistry and Molecular Biology
22.04.1994
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Subjects | |
Online Access | Get full text |
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Summary: | We have previously shown that the transmembrane domain and flanking residues of beta-1,2-N-acetylglucosaminyltransferase I
(GnTI) can localize a hybrid molecule to medial-Golgi cisternae (Burke, J., Pettitt, J. M., Schachter, H., Sarkar, M., and
Gleeson, P.A. (1992) J. Biol. Chem. 267, 24433-24440). Here, we have further examined the contribution of the cytoplasmic
tail, transmembrane domain, and the catalytically active, luminal domain of GnTI in medial-Golgi localization, by analyzing
the localization of hybrid molecules stably expressed in murine cells. In contrast to wild-type GnTI, which was efficiently
localized to the medial-Golgi and not detected at the cell surface, hybrid molecules containing any two of the three domains
of GnTI were localized to the medial-Golgi and were also present at low levels at the cell surface. Hybrid molecules containing
only the transmembrane domain or the luminal domain of GnTI showed partial Golgi retention together with an increased level
of cell surface expression compared with molecules containing two GnTI domains. The cytoplasmic tail independently was unable
to retain reporter sequences to the Golgi but increased the ability of constructs containing either the luminal or transmembrane
domain of GnTI to localize to the Golgi apparatus. Therefore, all three domains of GnTI contribute significantly to medial-Golgi
localization. Furthermore, GnTI hybrid molecules showing increased cell surface expression were more readily extracted in
a low salt buffer, suggesting that Golgi localized GnTI differs in physicochemical properties from cell surface GnTI. Based
on an aggregation model of localization, we propose that Golgi retention of these hybrid molecules is mediated by the interaction
of their GnTI domains with the corresponding domains of endogenous glycosyltransferase aggregates within the Golgi membranes
of the transfected cell. |
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Bibliography: | ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 |
ISSN: | 0021-9258 1083-351X |
DOI: | 10.1016/S0021-9258(17)32679-0 |