FIGURE 6.

Met→Leu substitutions at Met¹⁴⁴ or Met¹⁴⁵ induces CaM degradation. SDS-PAGE for apo- and calcium-saturated CaM-L8M144 (A), CaM-L8M145 (B), and CaM-L9 (B), corresponding to initial time-point (lane 1) and after 24 h incubation with the 20S proteasome/Hsp90 in the absence (lane 2) or presence (lane 3) of the proteasome inhibitor MG132 (40 nM). When indicated in panel A, Met¹⁴⁴ was oxidized to its corresponding methionine sulfoxide. Experimental conditions are as described in the legend to Fig. 5. Molecular mass markers are aprotinin (6 kDa) and lysozyme (14 kDa).