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Kathrin Tzschoppe, Sepp D. Kohlwein, Gerhard Rödel

Yeast Translational Activator Cbs2p: Mitochondrial Targeting and Effect of Overexpression

The yeast translational activator protein Cbs2p is imported into mitochondria without obvious proteolytic processing. To test the importance of amino-terminal amino acids for mitochondrial targeting we fused varying portions of the N-terminus with green fluorescent protein and examined the intracellular distribution of the reporter protein. We show that the 25 N-terminal amino acids are sufficient to direct the majority of the fusion protein into mitochondria. Cbs2p derivatives lacking 9 to 35 amino acids from the N-terminus fail to complement the respiratory deficiency of a ?cbs2 strain, but are still imported into mitochondria. Therefore Cbs2p contains at least one independent mitochondrial targeting information in addition to the N-terminal signal. We further analyzed the effect of over-expression of Cbs2p on mitochondrial function. Elevated concentrations of Cbs2p lead to slightly impaired mitochondrial gene expression, probably as the result of the formation of inactive Cbs2p aggregates.

Biological Chemistry, Walter de Gruyter

Print ISSN: 1431-6730
Volume: 381, 12/2000
Pages: 1175 - 1183

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