PubMed:10715549 JSONTXT

{"project":"bionlp-st-epi-2011-training","denotations":[{"id":"T1","span":{"begin":56,"end":62},"obj":"Protein"},{"id":"T2","span":{"begin":310,"end":316},"obj":"Protein"},{"id":"T3","span":{"begin":321,"end":327},"obj":"Protein"},{"id":"T4","span":{"begin":414,"end":420},"obj":"Protein"},{"id":"T5","span":{"begin":530,"end":536},"obj":"Protein"},{"id":"T6","span":{"begin":593,"end":599},"obj":"Protein"},{"id":"T7","span":{"begin":630,"end":636},"obj":"Protein"},{"id":"T8","span":{"begin":872,"end":878},"obj":"Protein"},{"id":"T9","span":{"begin":1064,"end":1070},"obj":"Protein"},{"id":"T10","span":{"begin":1123,"end":1129},"obj":"Protein"},{"id":"T11","span":{"begin":1240,"end":1246},"obj":"Protein"},{"id":"T12","span":{"begin":1251,"end":1257},"obj":"Protein"},{"id":"T13","span":{"begin":1303,"end":1309},"obj":"Protein"},{"id":"T14","span":{"begin":1329,"end":1335},"obj":"Protein"},{"id":"T15","span":{"begin":1437,"end":1443},"obj":"Protein"},{"id":"T16","span":{"begin":1449,"end":1455},"obj":"Protein"},{"id":"T17","span":{"begin":1646,"end":1652},"obj":"Protein"},{"id":"T18","span":{"begin":1790,"end":1796},"obj":"Protein"},{"id":"T19","span":{"begin":1802,"end":1808},"obj":"Protein"}],"text":"Additional N-glycosylation at Asn(13) rescues the human LHbeta-subunit from disulfide-linked aggregation.\nCG, LH, FSH, and TSH are a family of heterodimeric glycoprotein hormones that contain a common alpha-subunit, but differ in their hormone-specific beta-subunits. Despite the considerable homology between LHbeta and CGbeta, we previously demonstrated that, when expressed in GH(3) cells, the secreted form of LHbeta showed mispaired disulfide-linked aggregation in addition to monomer, whereas no aggregation was observed in CGbeta. To determine the domains which are associated with the LHbeta-aggregation and which prevent CGbeta-aggregation, mutant beta-subunits in glycosylation and carboxy-terminus were expressed in GH(3) cells, and the occurrence of aggregation was assessed by continuous labeling with [35S]methionine/cysteine, immunoprecipitation with anti-hCGbeta serum, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis in a non-reducing condition. No aggregation was seen when N-linked oligosaccharides were attached to the Asn(13) of LHbeta. Removal of the carbohydrate unit at the Asn(13) of CGbeta caused aggregation, although the amount was less than 10% of monomer. The carboxy-terminal regions of neither LHbeta nor CGbeta were associated with their aggregation. Both CGbeta wild-type (WT) and CGbeta lacking N-glycosylation at Asn(13) (CGbeta-N13) showed aggregates in lysate. However, in contrast to CGbeta-N13, CGbetaWT revealed no aggregation in medium. These results indicate that the backbone structure consisting of 114 amino acids and N-linked glycosylation at Asn(30) is involved in the aggregation of LHbeta. Moreover, N-glycosylation at Asn(13) does not prevent such aggregation, but instead plays an important role in correct folding for both LHbeta- and CGbeta-subunits to be secreted as monomer."}