Fig. 2. Summary of positions isotope-labeled for NMR studies on CLC-ec1.

Structures are shown in stereo view, focused in on one subunit of the homodimer.

a In a previous study, the five buried tyrosines were labeled with 3-fluorotyrosine (four solvent-exposed Tyr residues were mutated to Phe). Y445 and Y419 were identified as participating in H⁺-dependent conformational change (Elvington et al. 2009).

b & c In this study, Met residues (b) were ¹³C labeled on their methyl groups and Lys residues (c) were post-translationally ¹³C-dimethylated. The unresolved N- and C-termini of ClC-ec1 contain one Met and 2 Lys residues that are not shown in these diagrams. Residues K30, K131, K271, K442, and K455, examined in mutagenesis studies here, are indicated.