Table 5. Highly conserved interacting residues in EE and EM helix pairs.
An interacting residue is highly conserved only if its conservation is >80% and the overall conservation of the protein to which it belongs is less than 50%. For groupings of amino acids, see §2 and Table 1 ▶.
| Helix pairs | Conserved interacting residues | Polar (%) | Nonpolar (%) |
|---|---|---|---|
| N–N | 51 (acidic, 10; basic, 9; large polar, 2; small polar, 5; aromatic, 9; hydrophobic, 13; proline, 3) | 26 (51) | 22 (43) |
| N–MID (MID)† | 52 (acidic, 3; basic, 15; large polar, 2; small polar, 3; aromatic, 8; hydrophobic, 21) | 23 (44) | 29 (58) |
| N–C (C)† | 33 (acidic, 3; basic, 5; large polar, 1; small polar, 3; aromatic, 5; hydrophobic, 16) | 12 (36.3) | 21 (63.7) |
| Total | 136 (acidic, 16; basic, 29; large polar, 5; small polar, 11; aromatic, 22; hydrophobic, 50; proline, 3) | 61 (45) | 72 (53) |
| C–C | 48 (acidic, 1; basic, 3; large polar, 1; small polar, 1; aromatic, 4; hydrophobic, 38) | 6 (12.5) | 42 (87.5) |
| C–MID (MID)† | 45 (acidic, 1; basic, 6; large polar, 1; small polar, 1; aromatic, 6; hydrophobic, 30) | 9 (20) | 36 (80) |
| N–C (N)† | 45 (acidic, 4; basic, 6; large polar, 1; small polar, 4; aromatic, 9; hydrophobic, 18; proline, 3) | 15 (33.3) | 27 (60) |
| Total | 138 (acidic, 6; basic, 15; large polar, 3; small polar, 6; aromatic, 19; hydrophobic, 86; proline, 3) | 30 (22) | 105 (76) |
| N–MID (N)‡ | 32 (acidic, 5; basic, 3; small polar, 1; aromatic, 6; hydrophobic, 13; proline, 4) | 9 (28) | 19 (59) |
| C–MID (C)‡ | 31 (acidic, 2; large polar, 1; aromatic, 2; hydrophobic, 26) | 3 (9.7) | 28 (90.3) |
| Total | 63 (acidic, 7; basic, 3; large polar, 1; small polar, 1; aromatic, 8; hydrophobic, 39; proline, 4) | 12 (19) | 47 (75) |
Residues from N–MID and N–C helix pairs interacting with the N-terminus are considered. These residues interact with the N-terminus of the first helix through the middle [N–MID (MID)] or C-terminal [N–C (C)] region of the second helix.
Residues from C–MID and N–C helix pairs interacting with the C-terminus are considered. These residues interact with the C-terminus of the first helix through the middle [C–MID (MID)] or N-terminal [N–C (N)] region of the second helix.
Residues from N–MID and C–MID helix pairs interacting with the middle region of an α-helix are considered. These residues interact with the middle region of the first helix through the N-terminal [N–MID (N)] or C-terminal [C–MID (C)] regions of the second helix.