S0819

In the PLA, mouse monoclonal anti-Nav1.5 (1:50; ab62388, Abcam, UK) and rabbit monoclonal anti-Kir2.1 (1:100, ab109750, Abcam) primary antibodies were used. These antibodies bind to extracellular domains of Nav1.5 (residues 59-72 of human Nav1.5) and Kir2.1 (residues 107-122 of human Kir2.1 channels), respectively. Duolink secondary antibodies conjugated to PLA probes were also used. For electrophysiological experiments, rabbit anti-Nav1.5 (1.2 μg/mL, S0819, Sigma) and rabbit anti-Kir2.1 (1:1,000, ab65796, Abcam) were used. Both Nav1.5 (residues 493–511 located at the cytoplasmic loop between Domain I and II) and Kir2.1 (residues 1–81) antibodies bind to intracellular domains of the channels. For co-immunoprecipitation and western blot analysis rabbit polyclonal anti-CAMKIIδ (1:5,000 A010-56AP, Badrilla, UK) and rabbit polyclonal anti-GFP (1:1,000 ab290; Abcam) primary antibodies were used for detection of the C-terminal domain of CAMKIIδ and Kir2.1-CpVenus, respectively. Peroxidase-conjugated secondary antibodies (Jackson ImmunoResearch, USA) were used for detection of the proteins in lysates and HRP-protein A (Life Technologies) was used for detection of the immunoprecipitated proteins. Non-immune antibodies (IgG from rabbit or mouse serum) used as negative controls for co-immunoprecipitation experiments were obtained from Sigma-Aldrich.

Primary antibodies used were: mouse anti-GAPDH (G8795, Sigma-Aldrich; 1:10000 for western blot), mouse anti-c-Myc (M4439, Sigma-Aldrich; 1:6000 for western blot), mouse anti-Nav1.5 (S8809, Sigma-Aldrich; 1:2000 for western blot), rabbit anti-Nav1.5 (S0819, Sigma-Aldrich; 1:200 for immunostaining, 1:50 for STORM), chicken anti-Kir6.2 (C62; 1:50 for immunostaining and STORM), rabbit anti-Kir6.2 (Lee62; 1:50 for STORM), goat anti-Kir6.2 (N18, Santa Cruz; 1:500 for western blot), mouse anti-ankyrin-B (105/17, Neuromab; 1:2000 for western blot, 1:50 for STORM) and mouse anti-ankyrin-G (106/20, Neuromab; 1:2000 for western, 1:50 for STORM). Secondary antibodies used were donkey anti-mouse-HRP (715-035-150, Jackson, 1:10000), donkey anti-goat-HRP (705-035-147, Jackson, 1:10000), goat anti-chicken Alexa Fluor568 (A-11041, Thermo Scientific; 1:200), donkey anti-rabbit Alexa Fluor488 (711-545-152, Jackson; 1:200), and donkey anti-mouse Cy3 (715-165-151, Jackson; 1:200). All antibodies used in this study have been fully validated, either experimentally or in the literature. Details can be found in Figure 6—figure supplement 1 and Supplementary file 1.