An essential role of Sam50 in the protein sorting and assembly machinery of the mitochondrial outer membrane.
The preprotein translocase of the outer mitochondrial membrane (TOM complex) contains one essential subunit, the channel Tom40. The assembly pathway of the precursor of Tom40 involves the TOM complex and the sorting and assembly machinery (SAM complex) with the non-essential subunit Mas37. We have identified Sam50, the second essential protein of the mitochondrial outer membrane. Sam50 contains a beta-barrel domain conserved from bacteria to man and is a subunit of the SAM complex. Yeast mutants of Sam50 are defective in the assembly pathways of Tom40 and the abundant outer membrane protein porin, while the import of matrix proteins is not affected. Thus the protein sorting and assembly machinery of the mitochondrial outer membrane involves an essential, conserved protein.
Kozjak
Vera
V
Institut für Biochemie und Molekularbiologie, Universität Freiburg, D-79104 Freiburg, Germany.
Wiedemann
Nils
N
Milenkovic
Dusanka
D
Lohaus
Christiane
C
Meyer
Helmut E
HE
Guiard
Bernard
B
Meisinger
Chris
C
Pfanner
Nikolaus
N
D000595:Amino Acid Sequence; D008565:Membrane Proteins / Q000737:chemistry / Q000502:physiology*; D008928:Mitochondria / Q000502:physiology*; D008969:Molecular Sequence Data; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000502:physiology*; D017386:Sequence Homology, Amino Acid
D008565:Membrane Proteins; D029701:Saccharomyces cerevisiae Proteins