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The transmembrane domain of N –acetylglucosaminyltransferase I is the key determinant for its Golgi subcompartmentation
Author(s) -
Schoberer Jennifer,
Liebminger Eva,
Vavra Ulrike,
Veit Christiane,
Castilho Alexandra,
Dicker Martina,
Maresch Daniel,
Altmann Friedrich,
Hawes Chris,
Botchway Stanley W.,
Strasser Richard
Publication year - 2014
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.12671
Subject(s) - golgi apparatus , transmembrane domain , microbiology and biotechnology , transmembrane protein , biology , nicotiana benthamiana , homomeric , arabidopsis , transport protein , subcellular localization , cytoplasm , biochemistry , endoplasmic reticulum , receptor , protein subunit , gene , mutant
Summary Golgi‐resident type– II membrane proteins are asymmetrically distributed across the Golgi stack. The intrinsic features of the protein that determine its subcompartment‐specific concentration are still largely unknown. Here, we used a series of chimeric proteins to investigate the contribution of the cytoplasmic, transmembrane and stem region of Nicotiana benthamiana N –acetylglucosaminyltransferase I (Gn TI ) for its cis /medial‐Golgi localization and for protein–protein interaction in the Golgi. The individual Gn TI protein domains were replaced with those from the well‐known trans ‐Golgi enzyme α2,6–sialyltransferase ( ST ) and transiently expressed in Nicotiana benthamiana . Using co‐localization analysis and N –glycan profiling, we show that the transmembrane domain of Gn TI is the major determinant for its cis /medial‐Golgi localization. By contrast, the stem region of Gn TI contributes predominately to homomeric and heteromeric protein complex formation. Importantly, in transgenic Arabidopsis thaliana , a chimeric Gn TI variant with altered sub‐Golgi localization was not able to complement the Gn TI ‐dependent glycosylation defect. Our results suggest that sequence‐specific features in the transmembrane domain of Gn TI account for its steady‐state distribution in the cis /medial‐Golgi in plants, which is a prerequisite for efficient N –glycan processing in vivo .