FIGURE 1: Mechanism of mitochondria release from myosin during budding Mitochondria are transported into the growing bud by a type-V myosin Myo2 on the actin cable. Mmr1 bridges mitochondria and Myo2. After mitochondria enter the bud, Mmr1 is phosphorylated, most likely at the S414 residue, by Ste20 or Cla4. Phosphorylated Mmr1 is ubiquitinated by redundant E3 ubiquitin ligases Dma1 and Dma2. Polyubiquitinated Mmr1 is degraded by the proteasome, resulting in dissociation of mitochondria from Myo2. The released mitochondria move dynamically in the bud while Myo2 translocates to the bud-neck to play a role in cytokinesis. As Ste20 and Cla4 are mostly localized to the bud cortex region and nearly absent in the mother cell, phosphorylation of Mmr1 and its turnover take place only after the mitochondria reaches the bud, which may be the mechanism to ensure mitochondrial inheritance to daughter cells.