Figure 6. Molecular distances between the N- and C-termini of α_1C and the Ca_vβ-subunit N-tail of β_1b, β_2d and β₃.

(A) Schematic representation of Vα_1CC with Rβ arranged under a vertically sliced α_1C. The structures of TagRFP and Ca_vβ core MAGUK region were drawn based on PDB codes 1uisA [37] and 1t0j [62], respectively. FRET measurements with ECFP-labeled plekstrin homology domain in the inner leaflet of the plasma membrane [40], [63] showed that the N terminal tags of both the α_1C and Ca_vβ subunits are located within the 2× Förster distance (<100 Å for ECFP/EYFP) from the plasma membrane. (B) Schematic representation of the domain organization of β_1b, β_2d and β₃ aligned in regard to AID-binding guanylate kinase (GK) domain (green). Yellow box indicates the Src homology 3 (SH3) domain, purple the variable HOOK region, and blue the β₂CED [44]. Number of amino acids is shown inside boxes. Amino acids involved in AID-binding pocket are marked in GK by three horizontal lines (for details see [62], [64], [65]). (C) Schematic representation of the results of simultaneous measurements of the molecular distances between three fluorophores shown in panel (A) in Vα_1CC/α₂δ/Rβ in the presence of Rβ_1b (black lines), Rβ₃ (gray lines) and Rβ_2d (red lines).