B, HoxA-GFP and CitA-GFP (ca. 170 amino acids from the N-terminus of citrate synthase) were expressed over night at 30°C in minimal medium with 2% threonine and 0.2% glucose. Mitochondria were incubated with 100 μg/ml proteinase K (PK) for 20 min on ice. Crude extract (CE), supernatant 1 (S1) containing mitochondria, pellet 1 (P1), supernatant 2 (S2) and pellet 2 (P2) with mitochondria were analyzed by Western Blot using anti GFP antibodies. CitA-GFPc = cytoplasmic form; CitA-GFPi = imported version. 