Figure 2. Mmb1p colocalizes with the mitochondria network.
(A) Images of wildtype cells expressing mmb1-GFP3X and cox4-RFP, a mitochondria marker. Top panel shows control cells which do not have GFP-tagged mmb1. Control cells show no detectable auto-fluorescence that can be mistaken for mmb1-GFP3X. Bottom panel shows mmb1p-GFP3X colocalizes as dots and small bars on mitochondria.
(B) Images of wildtype cells expressing mmb1-GFP3X and cox4-RFP treated for 5 min with 25 μg/mL MBC, a microtubule-depolymerization drug. In the absence of microtubules, mitochondria begin to fragment and aggregate at the cell tips and mmb1p appears as diffused signal on mitochondria. Bar, 5 μm.
(C) Mitochondria isolated from wildtype cells expressing mitochondria marker cox4-GFP and mmb1-mCherry, or cox4-GFP and the microtubule bundling protein ase1-mCherry as control. Top panel shows ase1p does not bind to isolated mitochondria. Bottom panel shows mmb1p does bind to mitochondria. Isolated mitochondria appear as small aggregates.
(D) Western blots of tom70-GFP (a bona fide mitochondria membrane protein), mmb1-FLAG, and tubulin in cellular fractions containing the cytoplasm or the isolated mitochondria. Both tom70p and mmb1p appear in the isolated mitochondria fraction. Tubulin appears in the cytoplasmic fraction.