Table 2.

Fraction of yeast mitochondrial proteins with predicted transmembrane segments or signal peptides

Structure	Fraction (%) with structure
	Experimentally localized proteins				Predicted mitochondrial proteins*
	Prokaryote-derived†	Eukaryote-derived‡	Organism-specific§	All	Newly predicted	Predicted and known¶	All predicted
Transmembrane segments‖	36	55	27	37	46  ± 5	32  ± 4	40  ± 3
Signal peptides**	53	15	28	40	9  ± 2	53  ± 1	25  ± 2

^*Averages of 15 values from predictions made using predictive accuracies ranging from 50% to 75%. Each average is tabulated ± 1 SD. 

^†Proteins with ≥1 homolog detected in the prokaryotic genomes listed in Fig. 1A. 

^‡Proteins with no homologs in the prokaryotic genomes in Fig. 1A, but with eukaryotic homologs. 

^§Proteins with no homologs detected in genomes listed in Fig. 1A. 

^¶True positive predictions. 

^‖Fractions were calculated as the proteins with at least one predicted transmembrane segment, calculated as in Klein et al. (27) and implemented in psort-ii (15). 

^**Fractions were calculated as proteins with a score >0 from the mitdisc mitochondrial targeting signal predictor of psort-ii (15).