FIGURE 3:

Cyclin C stimulates Drp1 aggregate dissolution and filament formation. (A) Oligomerization was monitored using Western blot analysis of fractions following sedimentation. His₆–cyclin C, His₆–Mff, and/or GMP–PCP were incubated with His₆–Drp1 as indicated and then subjected to high-speed centrifugation. His₆–Drp1 and His₆–cyclin C in the resulting pellets (P) and the load (L) were visualized by Western blot and then quantified (below each lane) by calculating the ratio of His₆–Drp1 in the pellet (P) toy the amount loaded (L). GMP–PCP and GMP–PCP + His₆–cyclin C experiments were repeated three times (mean ± SEM; *p < 0.02 from no addition control). (B) Western blot analysis of SEC fractions obtained following incubation of His₆–Drp1, His₆–cyclin C, or both with or without GMP–PCP. Primary antibodies used are indicated on the right. (C, D) TEM images of His₆–Drp1 incubated with GMP–PCP/Mg²⁺ with or without His₆–cyclin C as indicated. White arrows indicate Drp1 rings. (E) Quantitation of Drp1 filament formation from TEM images counting 1485 and 493 particles without and with His₆–cyclin C, respectively, across 11 frames of identical magnification. Total particles include filaments and rings. Bars are mean ± SEM. Asterisks indicate p < 0.02.