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Table 5 Lipid contact statistics in TM and non-TM proteins with (a) head group and (b) tail group atoms

From: Lipid recognition propensities of amino acids in membrane proteins from atomic resolution data

  Transmembrane (TM) proteins Non-transmembrane (non-TM) proteins
  Obsa Expa Counts Signed chi-square P-value Obsa Expa Counts Signed chi-square P-value
(a) Head group
TRP†, ‡ 22 9.12 290 18.19 2.00E-05 3 2.23 84 0.27 6.06E-01
PHE†, ‡ 35 22.65 720 6.74 9.43E-03 13 9.06 341 1.72 1.90E-01
TYR†, ‡ 28 12.90 410 17.69 2.60E-05 21 7.25 273 26.08 3.27E-07
LEU 28 37.40 1189 -2.36 1.24E-01 20 21.85 823 -0.16 6.92E-01
ILE 11 23.18 737 -6.40 1.14E-02 9 11.58 436 -0.57 4.49E-01
CYS 2 4.25 135 -1.19 2.76E-01 2 4.51 170 -1.40 2.37E-01
MET 11 11.51 366 -0.02 8.80E-01 1 4.22 159 -2.46 1.17E-01
GLY 15 28.06 892 -6.07 1.37E-02 15 13.54 510 0.16 6.92E-01
VAL 16 26.70 849 -4.29 3.83E-02 14 15.11 569 -0.08 7.75E-01
SER 14 20.57 654 -2.10 1.47E-01 13 15.61 588 -0.44 5.08E-01
THR 16 19.53 621 -0.64 4.24E-01 5 10.62 400 -2.98 8.45E-02
ALA 16 29.85 949 -6.42 1.13E-02 12 17.55 661 -1.76 1.85E-01
HIS†, ‡ 16 8.05 256 7.85 5.09E-03 7 5.47 206 0.43 5.13E-01
ASN†, ‡ 22 11.45 364 9.73 1.82E-03 11 9.00 339 0.44 5.06E-01
PRO 9 15.98 508 -3.05 8.09E-02 6 10.36 390 -1.83 1.76E-01
GLN†, ‡ 14 8.30 264 3.91 4.80E-02 12 9.77 368 0.51 4.76E-01
ARG†, ‡ 32 13.24 421 26.58 2.53E-07 20 10.41 392 8.84 2.95E-03
LYS†, ‡ 20 12.20 388 4.98 2.56E-02 20 13.01 490 3.75 5.27E-02
ASP 6 11.73 373 -2.80 9.43E-02 5 11.79 444 -3.91 4.80E-02
GLU 8 14.34 456 -2.80 9.40E-02 7 13.04 491 -2.80 9.45E-02
(b) Tail group
TRP†, ‡ 42 12.9 290 65.46 5.93E-16 9 3.07 84 11.48 7.05E-04
PHE†, ‡ 63 32.1 720 29.82 4.75E-08 35 12.45 341 40.84 1.66E-10
TYR†, ‡ 21 18.3 410 0.41 5.22E-01 20 9.97 273 10.10 1.49E-03
LEU†, ‡ 85 53.0 1189 19.37 1.08E-05 68 30.05 823 47.92 4.43E-12
ILE†, ‡ 48 32.8 737 7.01 8.12E-03 33 15.92 436 18.33 1.86E-05
CYS 7 6.0 135 0.16 6.88E-01 5 6.21 170 -0.23 6.28E-01
MET†, ‡ 24 16.3 366 3.63 5.67E-02 13 5.81 159 8.92 2.83E-03
GLY 17 39.7 892 -13.01 3.10E-04 4 18.62 510 -11.48 7.03E-04
VAL†, ‡ 47 37.8 849 2.23 1.36E-01 34 20.78 569 8.42 3.72E-03
SER 26 29.1 654 -0.34 5.61E-01 8 21.47 588 -8.45 3.65E-03
THR 21 27.7 621 -1.61 2.05E-01 7 14.61 400 -3.96 4.66E-02
ALA 39 42.3 949 -0.25 6.14E-01 24 24.14 661 0.00 9.78E-01
HIS 6 11.4 256 -2.56 1.10E-01 3 7.52 206 -2.72 9.92E-02
ASN 7 16.2 364 -5.24 2.21E-02 3 12.38 339 -7.11 7.69E-03
PRO 8 22.6 508 -9.46 2.10E-03 9 14.24 390 -1.93 1.65E-01
GLN 6 11.8 264 -2.82 9.30E-02 2 13.44 368 -9.73 1.81E-03
ARG 5 18.8 421 -10.09 1.49E-03 7 14.31 392 -3.74 5.32E-02
LYS 4 17.3 388 -10.21 1.40E-03 8 17.89 490 -5.47 1.94E-02
ASP 1 16.6 373 -14.68 1.28E-04 2 16.21 444 -12.46 4.16E-04
GLU 6 20.3 456 -10.09 1.49E-03 3 17.93 491 -12.43 4.22E-04
  1. Statistically significant values (p-value <0.05 or 95% significance) are in bold font. The amino acids are sorted in the ascending order of the lipophilicity scale for POPC interface.
  2. †, ‡ The dagger and double-dagger symbols are used to show residues in which observed contacts are more than expected for TM and non-TM proteins, respectively.
  3. a Obs and Exp stand for observed and expected number of counts, respectively.