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Table 2 High conservation of residues facing the channel interior in all FNT channelsa

From: Anion-selective Formate/nitrite transporters: taxonomic distribution, phylogenetic analysis and subfamily-specific conservation pattern in prokaryotes

Residueb Residues in the positionc Conservation (%)d Remarkse
I45 (TM1) I(55), V, M, L 96.7 Hydrophobic
F75 (TM2a) F(79), Y 98.8 Part of the central constriction
C82 (TM2a) V(52), I, L 93.0 Hydrophobic
V83 (TM2a) V(39), I(33), L, M 86.7 Hydrophobic
D88 (Ω-loop) E(58), D 80.7 Acidic
L89 (Ω-loop) L(99) 99.9 Part of cytoplasmic slit (closed)
T91 (Ω-loop) T(98) 97.9 Part of cytoplasmic slit (closed)
S92 (Ω-loop) G(50), S, A 79.1 End of Ω-loop; small and weakly polar
N121 (TM3) N(99) 99.4 Hydrophilic, invariant
A171 (TM4) C(62), S, A, G 99.9 Close to S-loop; small and weakly polar
N172 (TM4) N(78) 78.4 Part of cytoplasmic slit (open)
V175 (TM4) V(81), I, M 99.9 Part of cytoplasmic slit (closed)
V179 (TM4) V(64), I, L, M 86.2 Hydrophobic
K191 (TM5a) K(83), R, E 96.4 Basic
M195 (TM5a) I(43), M, V, L 88.2 Hydrophobic
V199 (TM5a) I(39), L, V 76.9 Hydrophobic
F202 (TM5) F(78) 78.5 Part of central constriction ring
G206 (S-loop) G(74), S, T 79.0 Small and weakly polar
H209 (S-loop) H(99) 98.7 Part of central constriction ring
N213 (TM5b) N(76) 76.5 Hydrophilic
N262 (TM6) N(100) 100.0 Hydrophilic, invariant
  1. aAll 2206 FNT channels from bacteria, archaea and eukaryotes were considered for this analysis
  2. bResidue numbers correspond to that of formate channel structure as available in the PDB ID: 3KCU. Occurrence of these residues in the transmembrane segsments or the functionally important loop regions is also indicated. Residues forming the two constriction regions are shown in bold and italic
  3. cPercentage conservation of the most frequently observed residue(s) is indicated in brackets
  4. dPercentage conservation as observed in all 2206 FNT channels
  5. eChemical nature or the location with respect to the channel interior of the conserved residue is mentioned