Table 1 . Components of the TOM complex: transport of proteins through the outer membrane.

Protein	ORF	Known function	Null phenotype
Mim1	YOL026C	Insertion of transmembrane helix proteins into the outer membrane	Inviable
Mim2	YLR099W-A	Insertion of transmembrane helix proteins into the outer membrane	Inviable
Tom5	YPR133W-A		Viable, various defects
Tom6	YOR045W		Viable, various defects
Tom7	YNL070W		Viable, various defects
Tom20	YGR082W	Receptor for substrates with presequences	Viable, various defects
Tom22	YNL131W	Central receptor facing cytoplasm and IMS; interaction with TIM23 complex	Viable, various defectsa
Tom40	YMR203W	Translocation channel–β-barrel structure	Inviable
Tom70	YNL121C	Receptor for substrates lacking presequences	Viable, various defects
Tom71	YHR117W	Receptor	Viable, various defects

^aNull was inviable in large-scale studies, but is viable if obtained by loss of TOM22 plasmid during mitotic growth (van Wilpe et al. 1999).