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Table 1 Properties of PPI networks

From: Evidence of probabilistic behaviour in protein interaction networks

Network

Number of proteins

Number of interactions

r*

θ

γ (× 10-5)

γ(cal) (× 10-5)

H. sapiens

9263

34564

0.99

1.00 ± 0.02

1.49

1.45

D. melanogaster

6736

20308

0.99

1.01 ± 0.02

2.25

2.46

Yeast

      

   - DIP

4617

16311

0.99

1.02 ± 0.02

2.98

3.07

   - CORE

2449

5579

0.99

1.03 ± 0.06

8.41

8.97

   - Y2H

3277

4393

0.99

1.15 ± 0.08

7.22

11.4

E. coli

1473

5709

0.97

1.06 ± 0.04

6.09

8.79

Worm

      

   - Y2H

2624

3967

0.98

1.08 ± 0.07

9.59

12.6

   - CORE

727

814

0.99

1.03 ± 0.09

53.5

61.7

P. falciparum

1304

2745

0.99

0.99 ± 0.05

18.0

18.3

  1. *Pearson correlation coefficient for test of association between P(k1, k2) and k1k2, where P(k1, k2) is the probability of interaction between two proteins of degrees k1 and k2.
  2. Fitted values (from the Log-Log plots in Figure 1) occurring in the expression P(k1, k2) = γ(k1k2)θ. θ is given with 99% confidence intervals.
  3. Prediction of γ via γ(cal) = Ei<j(k i k j ), where E is the number of interactions in the network and the summation is over all pairs of proteins.