Fig. 1. The RRR motif in the first intracellular loop of Na_v1.8 serves as an ER-retention/retrieval signal. (A) COS-7 cells transfected with Na_v1.8-Myc were immunofluorescently labeled with antibodies against Myc and the ER marker calnexin, or the Golgi marker GM130. (B) Schematic of the intracellular segments of Na_v1.8 and the amino acid sequence of the first part of the first intracellular loop (1L). (C) Plasmids expressing Myc-CD8, Myc-CD8-KKTN, or a series of constructs with the C-terminus of CD8 linked to the second intracellular loop (2L) or the various segments of 1L of Na_v1.8 were transfected into COS-7 cells. Transfected cells were immunofluorescently labeled with antibody against Myc or calnexin. The images are representative of at least three independent experiments. Scale bars: 10 µm.