eGFP-Rab28 localization to larval zebrafish cone outer segments is partially dependent on GTP/GDP-binding. (A–C) Representative confocal z-projections of eGFP-Rab28 localization in 5 dpf zebrafish cone photoreceptors. The WT, putative GTP-preferring (Q72L) and GDP-preferring (T26N) variants of Rab28 all localize strongly to the outer segments of zebrafish cones, co-localizing with UV opsin labeling. Scale bars 5 μm. For WT, Q72L and T26N eGFP-Rab28 reporters a total of 14, 24 and 25 larvae were imaged, respectively. (D) Box and whisker plots of the ratio of eGFP-Rab28 intensity in the OS vs. synaptic region of larval cones. Box extremities represent 1st and 3rd quartiles; whiskers are maximum and minimum values. Data are from 60 cones per transgenic line. One-way ANOVA p-value < 0.0001. (E,F) Deconvolved, high resolution confocal z-projections of eGFP-Rab28 Q72L and T26N mutant localization in cones of 5 dpf larvae. A discrete localization pattern of the T26N mutant in COS is clearly observed (white arrowheads). Scale bars 4 μm.
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