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Tom40, the import channel of the mitochondrial outer membrane, plays an active role in sorting imported proteins
Author(s) -
Gabriel Kipros,
Egan Billie,
Lithgow Trevor
Publication year - 2003
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/cdg229
Subject(s) - biology
The T ranslocase of the O uter M itochondrial membrane (TOM complex) is centred on a channel, created by Tom40, serving as the only means of entry for proteins into the mitochondrion. Proteins destined for internal mitochondrial compartments interact subsequently with one of the two distinct protein T ranslocases of the I nner M itochondrial membrane (TIM23 and TIM54 complexes) or follow specialized paths into the intermembrane space. To investigate the sorting of precursor proteins to these various sub‐mitochondrial compartments, we created a library of tom40 mutants and screened for alleles selectively corrupt in protein sorting. One of the tom40 mutants, tom40–97 , carries a single point mutation (W 243 R) resulting in an ineffective transfer of precursors to the TIM23 complex. There is no defect on transfer of precursors to the TIM54 complex or insertion of proteins into the outer membrane. The Tom40 channel is not a passive pore, but plays an active role in protein sorting for all sub‐mitochondrial locations.