FIGURE 4.

Resistance of GluA1 tetramers to SDS with or without the ECD. A, BN-PAGE of GluA1, HA-GluA1-ΔATD, or HA-GluA1-ΔECD-EGFP with various concentrations of SDS added to solubilization buffer (also containing 6 mm DDM). B, tetramer fractions of GluA1 (open diamond, black solid line), HA-GluA1-ΔATD (gray triangle, gray dash line), and HA-GluA1-ΔECD-EGFP (black square, black dash line) were normalized to those at 0% SDS (see “Experimental Procedures”). Normalized fractions are plotted against the SDS concentration and fitted with sigmoid functions. The midpoints of the sigmoid functions fitted for the three constructs are ∼0.11, 0.08, and 0.11%, respectively. C, tetramer fractions of the same three constructs (indicated as in B) at various temperatures are normalized to those at 0 °C (see “Experimental Procedures”). Normalized tetramer fractions are plotted against temperature and fitted with sigmoid functions.