biostudies-literatureAryal RPNIGMS NIH HHS15317-29https://www.ebi.ac.uk/biostudies/studies/S-EPMC3346102biostudies-literatureUnknown287(19)The interaction of the endoplasmic reticulum molecular chaperone Cosmc with its specific client T-synthase (Core 1 β1-3-galactosyltransferase) is required for folding of the enzyme and eventual movement of the T-synthase to the Golgi, but the mechanism of interaction is unclear. Here we show that the lumenal domain of recombinant Cosmc directly interacts specifically in either free form or covalently bound to solid supports with denatured T-synthase but not with the active dimeric form of the enzyme. This leads to formation of a relatively stable complex of Cosmc and denatured T-synthase accompanied by formation of reactivated enzyme in an ATP-independent fashion that is not regulated by redox, calcium, pH, or intermolecular disulfide bond formation. The partly refolded and active T-synthaThe Journal of biological chemistryTight complex formation between Cosmc chaperone and its specific client non-native T-synthase leads to enzyme activity and client-driven dissociation.PMC3346102R01 GM068559Ju TCummings RDAryal RPfalseTight complex formation between Cosmc chaperone and its specific client non-native T-synthase leads to enzyme activity and client-driven dissociation.The interaction of the endoplasmic reticulum molecular chaperone Cosmc with its specific client T-synthase (Core 1 β1-3-galactosyltransferase) is required for folding of the enzyme and eventual movement of the T-synthase to the Golgi, but the mechanism of interaction is unclear. Here we show that the lumenal domain of recombinant Cosmc directly interacts specifically in either free form or covalently bound to solid supports with denatured T-synthase but not with the active dimeric form of the enzyme. This leads to formation of a relatively stable complex of Cosmc and denatured T-synthase accompanied by formation of reactivated enzyme in an ATP-independent fashion that is not regulated by redox, calcium, pH, or intermolecular disulfide bond formation. The partly refolded and active T-syntha2012-01-01T00:00:00Z2012 May2025-04-18T13:20:37.145Z2019-03-27T00:53:10ZS-EPMC33461022241613610.1074/jbc.m111.31258710.1074/jbc.M111.312587