Estimation of FLRev-erbβ HGS and MGC molecular mass with analytical gel filtration chromatography. 50 μl of 0.5–1 mg ml−1 FLRev-erbβ HGS (solid line) or MGC (dashed line) was injected onto a Shodex KW-803 HPLC column equilibrated in 50 mm bis-Tris, pH 7.0, 150 mm NaCl, 5% glycerol, and 0.5 mm TCEP. The approximate elution volumes of molecular mass standards are depicted, and the mass of FLRev-erbβ proteins are determined as described under “Experimental Procedures.”