By screening a collection of Saccharomyces cerevisiae mutants temperature sensitive for growth on a nonfermentable carbon source, we have isolated a gene (termed MAS37) which encodes a novel receptor for protein import into mitochondria. Mas37p is a 37-kD outer membrane protein with two putative membrane-spanning regions. Inactivation of the MAS37 gene renders cells temperature-sensitive for respiration-driven growth, inhibits import of precursors into isolated mitochondria, and is synthetically lethal with a deletion of one of the genes encoding the import receptors Mas70p or Mas20p. Inactivation of Mas37p with specific antibodies inhibits import of different precursors to different extents; the precursor specificity of Mas37p resembles that of the previously described import receptor Mas70p. Mas70p and Mas37p form a 1:1 complex in detergent extracts of mitochondria and overexpression of one protein enhances that of the other. We suggest that the Mas37p/Mas70p heterodimer functions as a receptor for protein import into yeast mitochondria and that the mitochondrial receptor system consists of hetero-oligomeric subcomplexes with distinct binding activities, but overlapping precursor specificities.
Mas37p, a novel receptor subunit for protein import into mitochondria.
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S Gratzer, T Lithgow, R E Bauer, E Lamping, F Paltauf, S D Kohlwein, V Haucke, T Junne, G Schatz, M Horst; Mas37p, a novel receptor subunit for protein import into mitochondria.. J Cell Biol 1 April 1995; 129 (1): 25–34. doi: https://doi.org/10.1083/jcb.129.1.25
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