Table 1 Usage of targeting signals in human and viral proteins

Protein count

28908

192

255

Targeting signals

Percentage of proteins containing signal

Predictor

Signal peptide

22.0%

25.0%

12.9%

SignalP [16]

Signal anchor

5.9%

8.8%

5.9%

SignalP

Mitochondrial targeting peptide

8.5%

12.0%

7.1%

Predotar [40]

0 TMD^a

78.0%

66.1%

76.5%

TMHMM [41]

1 TMD^a

10.0%

19.8%

16.1%

TMHMM

2 TMDs^a

2.4%

5.7%

5.9%

TMHMM

>2 TMDs^a

9.7%

8.3%

0.8%

TMHMM

GPI anchor

2.5–3.0%^b

3.1%

2.4%

GPI-SOM [42]

Prenyl group (PS00294)

0.8%

0.5%

0%

Prosite [43]

NLS

13.3%^c

8.3%

2.0%

PredictNLS [44]

KDEL-like (PS00014)

0.2%

0%

0%

Prosite

Peroxisomal targeting (PS00342)

2.2%

1.6%

2.8%

Prosite

Most prevalent eukaryotic functional domains

Percentage of proteins containing domain

Predictor

Immunoglobulin-like (IPR007110)

2.7%

5.7%

2.0%

InterPro [28]

Galactose oxidase (IPR011043)

0.3%

0%

1.6%

InterPro

Proteinase inhibititor I4, serpin (IPR000215)

0.2%

0%

1.6%

InterPro

Rhodopsin-like GPCR superfamily (IPR000276)

2.8%

2.1%

0%

InterPro