PubMed:12235182 JSONTXT

{"target":"https://pubannotation.org/docs/sourcedb/PubMed/sourceid/12235182","sourcedb":"PubMed","sourceid":"12235182","source_url":"http://www.ncbi.nlm.nih.gov/pubmed/12235182","text":"The N-linked oligosaccharides at the amino terminus of human apoB are important for the assembly and secretion of VLDL.\nWe determined the role of N-linked glycosylation of apolipoprotein B (apoB) in the assembly and secretion of lipoproteins using transfected rat hepatoma McA-RH7777 cells expressing human apoB-17, apoB-37, and apoB-50, three apoB variants with different ability to recruit neutral lipids. Substituting Asn residue with Gln at the single glycosylation site within apoB-17 (N(158)) decreased its secretion efficiency to a level equivalent to that of wild-type apoB-17 treated with tunicamycin, but had little effect on its synthesis or intracellular distribution. When selective N-to-Q substitution was introduced at one or more of the five N-linked glycosylation sites within apoB-37 (N(158), N(956), N(1341), N(1350), and N(1496)), secretion efficiency of apoB-37 from transiently transfected cells was variably affected. When all five N-linked glycosylation sites were mutated within apoB-37, the secretion efficiency and association with lipoproteins were decreased by \u003e50% as compared with wild-type apoB-37. Similarly, mutant apoB-50 with all of its N-linked glycosylation sites mutagenized showed decreased secretion efficiency and decreased lipoprotein association in both d \u003c 1.02 and d \u003e 1.02 g/ml fractions. The inability of mutant apoB-37 and apoB-50 to associate with very low-density lipoproteins was attributable to impaired assembly and was not due to the limitation of lipid availability. The decreased secretion of mutant apoB-17 and apoB-37 was not accompanied by accumulation within the cells, suggesting that the proportion of mutant apoB not secreted was rapidly degraded. However unlike apoB-17 or apoB-37, accumulation of mutant apoB-50 was observed within the endoplasmic reticulum and Golgi compartments. These data imply that the N-glycans at the amino terminus of apoB play an important role in the assembly and secretion of lipoproteins containing the carboxyl terminally truncated apoB.","tracks":[{"project":"FSU-PRGE","denotations":[{"id":"T1","span":{"begin":61,"end":65},"obj":"protein"},{"id":"T2","span":{"begin":114,"end":118},"obj":"protein"},{"id":"T3","span":{"begin":172,"end":188},"obj":"protein"},{"id":"T4","span":{"begin":190,"end":194},"obj":"protein"},{"id":"T5","span":{"begin":307,"end":314},"obj":"protein"},{"id":"T6","span":{"begin":316,"end":323},"obj":"protein"},{"id":"T7","span":{"begin":329,"end":336},"obj":"protein"},{"id":"T8","span":{"begin":344,"end":348},"obj":"protein"},{"id":"T9","span":{"begin":482,"end":489},"obj":"protein"},{"id":"T10","span":{"begin":577,"end":584},"obj":"protein"},{"id":"T11","span":{"begin":794,"end":801},"obj":"protein"},{"id":"T12","span":{"begin":875,"end":882},"obj":"protein"},{"id":"T13","span":{"begin":1004,"end":1011},"obj":"protein"},{"id":"T14","span":{"begin":1122,"end":1129},"obj":"protein"},{"id":"T15","span":{"begin":1149,"end":1156},"obj":"protein"},{"id":"T16","span":{"begin":1360,"end":1367},"obj":"protein"},{"id":"T17","span":{"begin":1372,"end":1379},"obj":"protein"},{"id":"T18","span":{"begin":1398,"end":1427},"obj":"protein"},{"id":"T19","span":{"begin":1557,"end":1564},"obj":"protein"},{"id":"T20","span":{"begin":1569,"end":1576},"obj":"protein"},{"id":"T21","span":{"begin":1672,"end":1676},"obj":"protein"},{"id":"T22","span":{"begin":1727,"end":1734},"obj":"protein"},{"id":"T23","span":{"begin":1738,"end":1745},"obj":"protein"},{"id":"T24","span":{"begin":1770,"end":1777},"obj":"protein"},{"id":"T25","span":{"begin":1909,"end":1913},"obj":"protein"},{"id":"T26","span":{"begin":2028,"end":2032},"obj":"protein"}],"attributes":[{"subj":"T1","pred":"source","obj":"FSU-PRGE"},{"subj":"T2","pred":"source","obj":"FSU-PRGE"},{"subj":"T3","pred":"source","obj":"FSU-PRGE"},{"subj":"T4","pred":"source","obj":"FSU-PRGE"},{"subj":"T5","pred":"source","obj":"FSU-PRGE"},{"subj":"T6","pred":"source","obj":"FSU-PRGE"},{"subj":"T7","pred":"source","obj":"FSU-PRGE"},{"subj":"T8","pred":"source","obj":"FSU-PRGE"},{"subj":"T9","pred":"source","obj":"FSU-PRGE"},{"subj":"T10","pred":"source","obj":"FSU-PRGE"},{"subj":"T11","pred":"source","obj":"FSU-PRGE"},{"subj":"T12","pred":"source","obj":"FSU-PRGE"},{"subj":"T13","pred":"source","obj":"FSU-PRGE"},{"subj":"T14","pred":"source","obj":"FSU-PRGE"},{"subj":"T15","pred":"source","obj":"FSU-PRGE"},{"subj":"T16","pred":"source","obj":"FSU-PRGE"},{"subj":"T17","pred":"source","obj":"FSU-PRGE"},{"subj":"T18","pred":"source","obj":"FSU-PRGE"},{"subj":"T19","pred":"source","obj":"FSU-PRGE"},{"subj":"T20","pred":"source","obj":"FSU-PRGE"},{"subj":"T21","pred":"source","obj":"FSU-PRGE"},{"subj":"T22","pred":"source","obj":"FSU-PRGE"},{"subj":"T23","pred":"source","obj":"FSU-PRGE"},{"subj":"T24","pred":"source","obj":"FSU-PRGE"},{"subj":"T25","pred":"source","obj":"FSU-PRGE"},{"subj":"T26","pred":"source","obj":"FSU-PRGE"}]}],"config":{"attribute types":[{"pred":"source","value type":"selection","values":[{"id":"FSU-PRGE","color":"#ecd593","default":true}]}]}}