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Figure 1.
Figure 1. Nondenaturing ESI-MS analysis of ligand binding to ROR
 .
(a) ROR  -stearate
complex (ROR -STE):
before addition of any ligand,  90%
of the detected species correspond to the ROR -STE
complex and 10% are related to unliganded ROR .
(b) ROR -ATRA
complex: after addition of 2.5 molar equivalents of ATRA
(molecular mass = 300.4 Da), the only detected species
corresponds to the ROR -ATRA
complex. Neither unliganded ROR nor
the ROR -STE
complex is present in the ESI mass spectrum. (c) ROR -ALRT
1550 complex (ROR -ALRT):
after addition of 2.5 molar equivalents of ALRT (molecular mass
= 340.5 Da), the only detected species corresponds to the ROR
-ALRT
complex. Neither unliganded ROR nor
the ROR -STE
complex is present in the ESI mass spectrum. The ESI-MS measured
masses for the different complexes are: 31,034.5  0.5
Da for ROR ,
31,321.4 0.9
Da for ROR -STE,
31,334.6 1.3
Da for ROR -ATRA
and 31,373.9 0.8
Da for ROR -ALRT.
Asterisk represents ROR without
the His[6]-tag; G, gluconoylation of the His[6]-tag; PG,
phosphogluconoylation of the His[6]-tag28.
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