Protein 4.2 localizes to the plasma membrane in Xenopus oocytes. The cRNAs corresponding to normal protein 4.2 and protein 4.2 Nippon were injected alone into Xenopus oocytes and then processed for confocal imaging as described in “Immunofluorescence and confocal microscopy.” The oocyte sections were incubated with the rabbit anti–protein-4.2 antibody (diluted 1:500) and detected using a goat antirabbit antibody conjugated to Alexa488. Panels A, C, E, G, and I are bright field images and panels B, D, F, H, and J are corresponding fluorescent images. (A-B) Injected with 1.5 ng normal protein-4.2 cRNA, (C-D) injected with 1.5 ng protein 4.2 Nippon cRNA, (E-F) injected with 1.5 ng protein 4.2 Tozeur cRNA, (G-H) injected with 1.5 ng protein 4.2 Komatsu cRNA, and (I-J) uninjected oocyte control. Both protein 4.2 and protein 4.2 Nippon had immunoreactive protein localized to the plasma membrane in oocytes. The majority of protein 4.2 Tozeur and protein 4.2 Komatsu immunostaining was intracellular, with very little present at the oocyte plasma membrane. No protein-4.2 staining was observed in control oocytes. Scale bar in panel K = 30 μM.