Panel A: Superdex-200 10/300 (GE healthcare) size exclusion chromatography profile of GNE at 6 mg per mL concentration in 20 mM HEPES buffer, pH 7.5, 500 mM NaCl, 5 mM MgCl2, 1 mM tris-(2-carboxyethyl)phosphine hydrochloride (TCEP). The lanes on the SDS-PAGE gel correspond to different fractions on the gel filtration profile. Panel B: Size exclusion column calibration curve and measurement of GNE kinase domain apparent molecular weight. Standard protein samples (black data points) used include thyroglobulin (670 kDa), globulin (158 kDa), conalbumin (75 kDa), ovalbumin (44 kDa), anhydrase (29 kDa), myoglobin (17 kDa), and ribonuclease (13.7 kDa). Green data points are values for GNE kinase domain in monomeric, dimeric and hexameric forms. The orange data point is for GNE kinase domain in putative tetrameric form.