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Free keywords:
BLUE NATIVE ELECTROPHORESIS; TOM COMPLEX; TPSB/OMP85 SUPERFAMILY;
ASSEMBLY MACHINERY; SAM COMPLEX; BIOGENESIS; DOMAIN; MDM10; PREDICTION;
RECEPTORS
Abstract:
The TOB-SAM complex is an essential component of the mitochondrial outer membrane that mediates the insertion of beta-barrel precursor proteins into the membrane. We report here its isolation and determine its size, composition, and structural organization. The complex from Neurospora crassa was composed of Tob55-Sam50, Tob38-Sam35, and Tob37-Sam37 in a stoichiometry of 1:1:1 and had a molecular mass of 140 kD. A very minorfraction of the purified complex was associated with one Mdm10 protein. Using molecular homology modeling for Tob55 and cryoelectron microscopy reconstructions of the TOB complex, we present a model of the TOB-SAM complex that integrates biochemical and structural data. We discuss our results and the structural model in the context of a possible mechanism of the TOB insertase.
