Lipidation and surface charge, alone, drive compartmentalization of PMPs. (A) Schematic of amphibian rod. S, Synaptic spherule; Ax, axon; N, nucleus; M, myoid; E, ellipsoid; ND, nascent discs; CC, connecting cilium; DM, mature disc membranes; and PM, plasma membrane. Cyan: Apical membrane. NDs are open to the extracellular milieu and contiguous with the CC and PM. DMs are enclosed within and separate from the OS PM and each other. (B) Confocal images of rod cells expressing PMP probes. Scale bars, 10 µm. (C) Box-whisker plots of average fluorescence in synapse divided by average fluorescence of OS. In all box-whisker plots, circles represent individual cells, red line is median, box limits are 25th and 75th percentiles, whiskers are interquartile range, excluding outliers (+), and green asterisks are means. Presence of differences among all probes was tested by one-way ANOVA, α = 0.05. Black asterisks indicate significant differences from NL0, determined by Tukey-corrected post hoc two-tailed t test. n for each construct: GG+8, 14; Far+8, 13; Far+4, 21; NL0, 29; Myr+8, 27; Far-8, 16; ctTγ, 17; GG-8, 22; Far0, 42; GG0, 20; Myr-8, 15; ntTα, 18; Myr0, 28; and GRK1ct18, 30. ns, not significant.