Cover legend: Ribbon diagram of an assembled tetramer of the voltage-gated potassium channel, Kv1.2, with complemented fragments of pHluorin (yellow) on the extracellular S1–S2 loops. Individual α subunits are shown in green, orange, magenta, and cyan. Complementation of the fluorophore allows visualization of heteromeric channel assembly, localization, and trafficking. For more information, see the article by Jenkins et al. in issue 37 (pages 13224–13235).